The time limit is enforced in the client. The name of the scache 8 connection cache service. This service maintains a limited pool of cached sessions. How frequently the scache 8 server logs usage statistics with connection cache hit and miss rates for logical destinations and for physical endpoints. The maximal time-to-live value that the scache 8 connection cache server allows. The purpose of this additional control is to protect the infrastructure against careless people.
After the message is queued, send the entire message to the specified transport:destination. The transport name specifies the first field of a mail delivery agent definition in master. The meaning of an empty next-hop filter destination is version dependent. Specify zero or more directories separated by a colon character, or an empty value to use Cyrus SASL's built-in search path.
This feature is available in Postfix 2. The directory with Postfix support programs and daemon programs. These should not be invoked directly by humans. The directory must be owned by root.
How a Postfix daemon process handles errors while opening lookup tables: gradual degradation or immediate termination. Gradual degradation: a daemon process logs a message of type "error" and continues execution with reduced functionality. Features that do not depend on the unavailable table will work normally, while features that depend on the table will result in a type "warning" message. Immediate termination: a daemon process logs a type "fatal" message and terminates immediately.
This option reduces the number of possible code paths through Postfix, and may therefore be slightly more secure than the default. For the sake of sanity, the number of type "error" messages is limited to 13 over the lifetime of a daemon process. How much time a Postfix daemon process may take to handle a request before it is terminated by a built-in watchdog timer.
The directory with Postfix-writable data files for example: caches, pseudo-random numbers. The right-hand side result from " type:table " lookups is ignored. Use "command.. The default database type for use in newaliases 1 , postalias 1 and postmap 1 commands. On many UNIX systems the default type is either dbm or hash. The default setting is frozen when the Postfix system is built. How often the Postfix queue manager's scheduler is allowed to preempt delivery of one message with another.
Each transport maintains a so-called "available delivery slot counter" for each message. One message can be preempted by another one when the other message can be delivered using no more delivery slots i. The cost of 0 is used to disable the preempting scheduling completely. The minimum value the scheduling algorithm can use is 2 - use it if you want to maximize the message throughput rate. Although there is no maximum, it doesn't make much sense to use values above say The only reason why the value of 2 is not the default is the way this parameter affects the delivery of mailing-list mail.
The default value of 5 turns out to provide reasonable message response times while making sure the mailing-list deliveries are not extended by more than percent even in the worst case.
This parameter speeds up the moment when a message preemption can happen. Note that the full amount will still have to be accumulated before another preemption can take place later. Optional filter to replace the delivery status code or explanatory text of successful or unsuccessful deliveries. This does not allow the replacement of a successful status code 2. X with an unsuccessful status code 4. X or vice versa. These parameters support the same filter syntax as described here.
Specify zero or more " type:table " lookup table names, separated by comma or whitespace. For each successful or unsuccessful delivery to a recipient, the tables are queried in the specified order with one line of text that is structured as follows:.
The first table match wins. The lookup result must have the same structure as the query, a successful status code 2. X must be replaced with a successful status code, an unsuccessful status code 4. X must be replaced with an unsuccessful status code, and the explanatory text field must be non-empty. Other results will result in a warning. Example 1: convert specific soft TLS errors into hard errors, by overriding the first number in the enhanced status code.
Example 2: censor the per-recipient delivery status text so that it does not reveal the destination command or filename when a remote sender requests confirmation of successful delivery.
This feature will change the enhanced status code and text that is logged to the maillog file, and that is reported to the sender in delivery confirmation or non-delivery notifications. How many pseudo-cohorts must suffer connection or handshake failure before a specific destination is considered unavailable and further delivery is suspended. Specify zero to disable this feature. A destination's pseudo-cohort failure count is reset each time a delivery completes without connection or handshake failure for that specific destination.
The default setting is compatible with earlier Postfix versions. The default maximal number of parallel deliveries to the same destination. This is the default limit for delivery via the lmtp 8 , pipe 8 , smtp 8 and virtual 8 delivery agents. The per-destination amount of delivery concurrency negative feedback, after a delivery completes with a connection or handshake failure.
Feedback values are in the range To make the scheduler completely immune to connection or handshake failures, specify a zero feedback value and a zero failed pseudo-cohort limit. The per-destination amount of delivery concurrency positive feedback, after a delivery completes without connection or handshake failure. The concurrency increases until it reaches the per-destination maximal concurrency limit. The default amount of delay that is inserted between individual message deliveries to the same destination and over the same message delivery transport.
The resulting behavior depends on the value of the corresponding per-destination recipient limit. Different domains are delivered in parallel, subject to the process limits specified in master. With a corresponding per-destination recipient limit equal to 1, the rate delay specifies the time between deliveries to the same recipient. Different recipients are delivered in parallel, subject to the process limits specified in master.
To enable the delay, specify a non-zero time value an integral value plus an optional one-letter suffix that specifies the time unit. NOTE: the delay is enforced by the queue manager. The delay timer state does not survive " postfix reload " or " postfix stop ".
The default maximal number of recipients per message delivery. It changes the meaning of the corresponding per-destination concurrency limit, from concurrency of deliveries to the same domain into concurrency of deliveries to the same recipient. It changes the meaning of the corresponding per-destination rate delay, from the delay between deliveries to the same domain into the delay between deliveries to the same recipient.
Again, different recipients are delivered in parallel, subject to the process limits specified in master. It changes the meaning of other corresponding per-destination settings in a similar manner, from settings for delivery to the same domain into settings for delivery to the same recipient.
The default value for the extra per-transport limit imposed on the number of in-memory recipients. This extra recipient space is reserved for the cases when the Postfix queue manager's scheduler preempts one message with another and suddenly needs some extra recipient slots for the chosen message in order to avoid performance degradation.
How many recipients a message must have in order to invoke the Postfix queue manager's scheduling algorithm at all. Messages which would never accumulate at least this many delivery slots subject to slot cost parameter as well are never preempted. The default rights used by the local 8 delivery agent for delivery to an external file or command.
These rights are used when delivery is requested from an aliases 5 file that is owned by root , or when delivery is done on behalf of root. The default maximal number of Postfix child processes that provide a given service. This limit can be overruled for specific services in the master. Note: when an enhanced status code is specified in an RBL reply template, it is subject to modification. The following transformations are needed when the same RBL reply template is used for client, helo, sender, or recipient access restrictions.
The default per-transport upper limit on the number of in-memory recipients. The default per-transport maximum delay between refilling recipients.
When not all message recipients fit into memory at once, keep loading more of them at least once every this many seconds. The default per-transport limit on the number of recipients refilled at once. When not all message recipients fit into memory at once, keep loading more of them in batches of at least this many at a time. Specify a string of the form transport:nexthop , where transport is the name of a mail delivery transport defined in master. The :nexthop destination is optional; its syntax is documented in the manual page of the corresponding delivery agent.
The default amount of delay that is inserted between individual message deliveries over the same message delivery transport, regardless of destination.
The two default VERP delimiter characters. The name of the defer service. This service is implemented by the bounce 8 daemon and maintains a record of failed delivery attempts and generates non-delivery notifications. The names of message delivery transports that should not deliver mail unless someone issues " sendmail -q " or equivalent. Specify zero or more mail delivery transport names that appear in the first field of master. The maximal number of digits after the decimal point when logging sub-second delay values.
Specify a number in the range The time after which the sender receives a copy of the message headers of mail that is still queued. To enable this feature, specify a non-zero time value an integral value plus an optional one-letter suffix that specifies the time unit. The maximal number of attempts to acquire an exclusive lock on a mailbox file or bounce 8 logfile. The time between attempts to acquire an exclusive lock on a mailbox file or bounce 8 logfile. As of Postfix 2.
Turn off MIME processing while receiving mail. This means that no special treatment is given to Content-Type: message headers, and that all text after the initial message headers is considered to be part of the message body. Mime input processing is enabled by default, and is needed in order to recognize MIME headers in message content. Enable a workaround for future libc incompatibility.
If this promise is broken, specify "yes" to enable a workaround for DNS reputation lookups. The name of the dnsblog 8 service entry in master. This feature is available in Postfix 3. It was backported to Postfix versions 3. Don't remove queue files and save them to the "saved" mail queue. This is a debugging aid. To inspect the envelope information and content of a Postfix queue file, use the postcat 1 command.
The sender address of postmaster notifications that are generated by the mail system. All mail to this address is silently discarded, in order to terminate mail bounce loops. The maximal number of addresses remembered by the address duplicate filter for aliases 5 or virtual 5 alias expansion, or for showq 8 queue displays. The recipient of mail addressed to the null address. Postfix does not accept such addresses in SMTP commands, but they may still be created locally as the result of configuration or software error.
Report mail delivery errors to the address specified with the non-standard Errors-To: message header, instead of the envelope sender address this feature is removed with Postfix version 2. This affects the conversion of domain names that contain for example the German sz and the Greek zeta. Enable long, non-repeating, queue IDs queue file names. The benefit of non-repeating names is simpler logfile analysis and easier queue migration there is no need to run "postsuper" to change queue file names that don't match their message file inode number.
New queue files are created with names such as 3Pt2mN2VXxznjll. These are encoded in a character alphabet that contains digits , upper-case letters B-Z and lower-case letters b-z. The name format is: 6 or more characters for the time in seconds, 4 characters for the time in microseconds, the 'z'; the remainder is the file inode number encoded in the first 51 characters of the character alphabet. The mailq postqueue -p output has a wider Queue ID column.
The number of whitespace-separated fields is not changed. Existing long queue file names are renamed to the short form while running "postfix reload" or "postsuper". New queue files are created with names such as C3CD21F3E90 from a hexadecimal alphabet that contains digits and upper-case letters A-F. The name format is: 5 characters for the time in microseconds; the remainder is the file inode number.
Enable support for the original recipient address after an address is rewritten to a different address for example with aliasing or with canonical mapping. Postfix versions before 2. Enable non-delivery, success, and delay notifications that link to the original message by including a References: and In-Reply-To: header with the original Message-ID value. There are advantages and disadvantages to consider.
The recipient of postmaster notifications about mail delivery problems that are caused by policy, resource, software or protocol errors. The name of the error 8 pseudo delivery agent. This service always returns mail as undeliverable. When delivering to an alias " aliasname " that has an "owner- aliasname " companion alias, set the envelope sender address to the expansion of the "owner- aliasname " alias. Normally, Postfix sets the envelope sender address to the name of the "owner- aliasname " alias.
The list of environment variables that a Postfix process will export to non-Postfix processes. The TZ variable is needed for sane time keeping on System-V-ish systems.
The maximal number of recipient addresses that Postfix will extract from message headers when mail is submitted with " sendmail -t ". Optional list of relay hosts for SMTP destinations that can't be found or that are unreachable. With Postfix 2. By default, mail is returned to the sender when a destination is not found, and delivery is deferred when a destination is unreachable. The fallback relays must be SMTP destinations. Specify a domain, host, host:port, [host]:port, [address] or [address]:port; the form [host] turns off MX lookups.
Note: before Postfix 2. Optional message delivery transport that the local 8 delivery agent should use for names that are not found in the aliases 5 or UNIX password database.
The precedence of local 8 delivery features from high to low is: aliases,. Optional lookup tables with per-recipient message delivery transports for recipients that the local 8 delivery agent could not find in the aliases 5 or UNIX password database. Optional list of destinations that are eligible for per-destination logfiles with mail that is queued to those destinations. By default, Postfix maintains "fast flush" logfiles only for destinations that the Postfix SMTP server is willing to relay to i.
The default time unit is days. The time after which a non-empty but unread per-destination "fast flush" logfile needs to be refreshed. The contents of a logfile are refreshed by requesting delivery of all messages listed in the logfile. The default time unit is hours. Force specific internal tests to fail, to test the handling of errors that are difficult to reproduce otherwise. The name of the flush 8 service.
This service maintains per-destination logfiles with the queue file names of mail that is queued for those destinations.
The local 8 delivery agent search list for finding a. The first file that is found is used. With older Postfix releases, the behavior is as if this parameter is set to "no". The old setting can be expensive with deeply nested aliases or. When an alias or. Queue hashing is implemented by creating one or more levels of directories with one-character names.
Originally, these directory names were equal to the first characters of the queue file name, with the hexadecimal representation of the file creation time in microseconds. With long queue file names, queue hashing produces the same results as with short names.
The file creation time in microseconds is converted into hexadecimal form before the result is used for queue hashing. The base 16 encoding gives finer control over the number of subdirectories than is possible with the base 52 encoding of long queue file names. Claims about improvements in file system technology suggest that hashing of the incoming and active queues is no longer needed.
Fewer hashed directories speed up the time needed to restart Postfix. The maximal number of address tokens are allowed in an address message header. Information that exceeds the limit is discarded. The limit is enforced by the cleanup 8 server. The format of the Postfix-generated From: header. Postfix generates the format " From: address " when name information is unavailable or the envelope sender address is empty.
This is the same behavior as prior to Postfix 3. In the standard form, the name will be quoted if it contains specials as defined in RFC , or the "!
The maximal amount of memory in bytes for storing a message header. If a header is larger, the excess is discarded. Optional pathname of a mailbox file relative to a local 8 user's home directory. The maximal number of Received: message headers that is allowed in the primary message headers. A message that exceeds the limit is bounced, in order to stop a mailer loop. The location of Postfix HTML files that describe how to build, configure or operate a specific Postfix subsystem or feature.
This behavior is required by the SMTP standard. This violates the SMTP standard and can result in mis-delivery of mail. Examples of relevant environment variables:. Time to pause before accepting a new message, when the message arrival rate exceeds the message delivery rate.
The network interface addresses that this mail system receives mail on. Specify "all" to receive mail on all network interfaces default , and "loopback-only" to receive mail on loopback network interfaces only Postfix version 2. The parameter also controls delivery of mail to user [ip. Note 2: address information may be enclosed inside [] , but this form is not required here.
Support for IPv6 is available in Postfix version 2. On a multi-homed firewall with separate Postfix instances listening on the "inside" and "outside" interfaces, this can prevent each instance from being able to reach remote SMTP servers on the "other side" of the firewall. This preserves the Postfix SMTP client's loop detection, by ensuring that each side of the firewall knows that the other IP address is still the same host.
The Internet protocols Postfix will attempt to use when making or accepting connections. Specify one or more of "ipv4" or "ipv6", separated by whitespace or commas. The form "all" is equivalent to "ipv4, ipv6" or "ipv4", depending on whether the operating system implements IPv6.
For backwards compatibility with these releases, the Postfix 2. This compatibility workaround will be phased out as IPv6 deployment becomes more common. The email address form that will be used in non-debug logging info, warning, etc. As of Postfix 3. The external and internal forms are identical for the vast majority of email addresses that contain no spaces or other special characters in the localpart.
The logging in external form is consistent with the address form that Postfix 3. This is therefore the more useful form for non-debug logging. Postfix uses the unquoted form internally, because an attacker can specify an email address in different forms by playing games with quotes and backslashes. An attacker should not be able to use such games to circumvent Postfix access policies.
The initial per-destination concurrency level for parallel delivery to the same destination. Specify zero or more of the following, separated by whitespace or comma.
The user is warned. The time after which a client closes an idle internal communication channel. The purpose is to allow Postfix daemon processes to terminate voluntarily after they become idle. This is used, for example, by the Postfix address resolving and rewriting clients. The time limit for sending or receiving information over an internal communication channel.
The purpose is to break out of deadlock situations. If the time limit is exceeded the software aborts with a fatal error. The time after which a client closes an active internal communication channel.
The purpose is to allow Postfix daemon processes to terminate voluntarily after reaching their client limit. Optional setting that avoids lookups in the services 5 database. This feature was implemented to address inconsistencies in the name of the port "" service. The ABNF is:. The comma is required.
Whitespace is optional but it cannot appear inside a service name or port number. Upon input, long lines are chopped up into pieces of at most this length; upon delivery, long lines are reconstructed. Each time a database becomes full, its size limit is doubled.
See there for details. When a remote LMTP server announces no DSN support, assume that the server performs final delivery, and send "delivered" delivery status notifications instead of "relayed". The default setting is backwards compatible to avoid the infinitesimal possibility of breaking existing LMTP-based content filters. When the LMTP client receives a request for the same connection the connection is reused.
This parameter is available in Postfix version 2. The effectiveness of cached connections will be determined by the number of remote LMTP servers in use, and the concurrency limit specified for the Postfix LMTP client. Cached connections are closed under any of the following conditions:. Most of these limitations have been with the Postfix connection cache that is shared among multiple LMTP client programs. When no connection can be made within the deadline, the LMTP client tries the next address on the mail exchanger list.
When no response is received within the deadline, a warning is logged that the mail may be delivered multiple times. The maximal number of parallel deliveries to the same destination via the lmtp message delivery transport. This limit is enforced by the queue manager. The message delivery transport name is the first field in the entry in the master. The maximal number of recipients per message for the lmtp message delivery transport.
A case insensitive list of LHLO keywords pipelining, starttls, auth, etc. Optional list of relay hosts for LMTP destinations that can't be found or that are unreachable. In main. The fallback relays must be TCP destinations, specified without a leading "inet:" prefix.
Specify a host or host:port. The default value is the machine hostname. Specify a hostname or [ip. This information can be specified in the main. If a remote host or domain has no username:password entry, then the Postfix LMTP client will not attempt to authenticate to the remote host.
Typically this specifies the name of a configuration file or rendezvous point. SASL security options; as of Postfix 2.
The available types are listed with the " postconf -A " command. This allows an lmtp 8 delivery agent, used for content filter message injection, to forward the name, address, protocol and HELO name of the original client to the content filter and downstream LMTP server. Before you change the value to yes, it is best to make sure that your content filter supports this command.
Specify a symbolic name see services 5 or a numeric port. Optional shell program for local 8 delivery to non-Postfix commands. Note: when a shell program is specified, it is invoked even when the command contains no shell built-in commands or meta characters. Optional filter for the local 8 delivery agent to change the status code or explanatory text of successful or unsuccessful deliveries. A low limit of 2 is recommended, just in case someone has an expensive shell command in a.
You don't want to run lots of those at the same time. The maximal number of recipients per message delivery via the local mail delivery transport. The purist and default setting: rewrite headers only in mail from Postfix sendmail and in SMTP mail from this machine.
Note: this setting will not prevent remote mail header address rewriting when mail from a remote client is forwarded by a neighboring system.
A list of lookup tables that are searched by the UNIX login name, and that return a list of allowed envelope sender patterns separated by space or comma. These sender patterns are enforced by the Postfix postdrop 1 command. The default is backwards-compatible: every user may specify any sender envelope address. Specify domain as a wild-card for domains that do not have a valid recipient list.
If this parameter is non-empty the default , then the Postfix SMTP server will reject mail for unknown local users. The default setting assumes that you use the default Postfix local delivery agent for local delivery. Beware: if the Postfix SMTP server runs chrooted, you need to access the passwd file via the proxymap 8 service, in order to overcome chroot access restrictions. The alternative, maintaining a copy of the system password file in the chroot jail is not practical.
By default, local mail is delivered to the transport called "local", which is just the name of a service that is defined the master. Optional catch-all destination for unknown local 8 recipients. The mail system name that is displayed in Received: headers, in the SMTP greeting banner, and in bounced mail. Specify the name of an unprivileged user account that does not share a user or group ID with other accounts, and that owns no other files or processes on the system. In particular, don't specify nobody or daemon.
When this parameter value is changed you need to re-run " postfix set-permissions " with Postfix version 2. The directory where local 8 UNIX-style mailboxes are kept. The default setting depends on the system type.
Note: maildir delivery is done with the privileges of the recipient. Postfix will not create it. The version of the mail system. Stable releases are named major. Experimental releases also include the release date. The version string can be used in, for example, the SMTP greeting banner. Optional external command that the local 8 delivery agent should use for mailbox delivery.
The command is run with the user ID and the primary group ID privileges of the recipient. This is not a problem, because 1 mail for root should always be aliased to a real user and 2 don't log in as root, use "su" instead. This is to make it easier to specify shell syntax see example below.
If you can, avoid shell meta characters because they will force Postfix to run an expensive shell process. If you're delivering via "procmail" then running a shell won't make a noticeable difference in the total cost. Optional lookup tables with per-recipient external commands to use for local 8 mailbox delivery.
How to lock a UNIX-style local 8 mailbox before attempting delivery. For a list of available file locking methods, use the " postconf -l " command. This setting is ignored with maildir style delivery, because such deliveries are safe without explicit locks. The maximal size of any local 8 individual mailbox or maildir file, or zero no limit. In fact, this limits the size of any file that is written to upon local delivery, including files written by external commands that are executed by the local 8 delivery agent.
Optional message delivery transport that the local 8 delivery agent should use for mailbox delivery to all local recipients, whether or not they are found in the UNIX passwd database. Optional lookup tables with per-recipient message delivery transports to use for local 8 mailbox delivery, whether or not the recipients are found in the UNIX passwd database.
The name of an optional logfile that is written by the Postfix postlogd 8 service. An empty value selects logging to syslogd 8. Stdout logging requires that Postfix is started with "postfix start-fg". Note 2: Some Postfix non-daemon programs may still log information to syslogd 8 , before they have processed their configuration parameters and command-line options.
The command is run with the rotated logfile name as its first argument. This is a safety feature to contain the damage from a single configuration mistake.
Specify one or more prefix strings, separated by comma or whitespace. See strftime 3 for syntax. Sendmail compatibility feature that specifies where the Postfix mailq 1 command is installed. This command can be used to list the Postfix mail queue. By default, address masquerading is limited to envelope sender addresses, and to header sender and header recipient addresses. This allows you to use address masquerading on a mail gateway while still being able to forward mail to users on individual machines.
Selectively disable master 8 listener ports by service type or by service name and type. As with other Postfix matchlists, a search stops at the first match. By default, all master 8 listener ports are enabled. This is intentional. The maximum amount of time that an idle Postfix daemon process waits for an incoming connection before terminating voluntarily. This parameter is ignored by the Postfix queue manager and by other long-lived Postfix daemon processes.
The maximal number of incoming connections that a Postfix daemon process will service before terminating voluntarily. Specify a list of header names, separated by comma or space. Names are matched in a case-insensitive manner. The list of supported header names is limited only by available memory. The set of characters that Postfix will reject in message content. Note 1: this feature does not recognize text that requires MIME decoding.
The maximal size in bytes of a message, including envelope information. Note: be careful when making changes. Excessively small values will result in the loss of non-delivery notifications, when a bounce message size exceeds the local or remote MTA's message size limit.
The set of characters that Postfix will remove from message content. The location of non-executable files that are shared among multiple Postfix instances, such as postfix-files, dynamicmaps.
This directory should contain only Postfix-related files. Therefore, we enable it only after tightening the security of the server. In short, the Postfix queue file size limit exceeded indicates the email message size is larger than configured. Today, we saw how our Support Engineers change this value and fix the error.
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Is your server reporting Postfix queue file size limit exceeded error? This can be simply resolved by changing the message size limit in the config file. Mails are so crucial today and so are the mail errors. Connect and share knowledge within a single location that is structured and easy to search. We recommend contacting the other email provider for further information about the cause of this error.
The error that the other server returned was: 5. I found the following suggestion , but am unclear as to where it needs to be added in the main.
Add it anywhere in main. Note: be careful when making changes. Excessively small values will result in the loss of non-delivery notifications, when a bounce message size exceeds the local or remote MTA's message size limit. Additionally, the default mailbox size of 50M may prevent mail from being delivered, especially after increasing the permitted message size. Put it anywhere in the main.
Be careful if setting this limit to a high number. You need at least 1. If you don't have that free space, then all messages are rejected even if they are only a few kilobyte in size. And if you receive one message of this size and then the space exceeds during final mailbox delivery all further messages are rejected. Due to missing space. Also note: Email is not a file transfer protocol.
See this QA: Why do we still have such small email attachment filesize restrictions? Took me ages to find this, no one seems to talk about it. Sign up to join this community.
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