LKBEN11588: How long does a mailserver try to deliver mails via SMTP.
Symptom
Some mailserver is down and the recovery takes longer.
Cause
Every server can fail. A mailserver should have a backup.
Solution
There are some guidelines for delivering mails. These parameters can be changed and therefore the real answer depends on the mailservers involved.
The default maximal_queue_lifetime of postfix is 5 days.
The following information is taken from https://www.rfc-editor.org/rfc/rfc5321#section-4.5.4
The sender MUST delay retrying a particular destination after one
attempt has failed. In general, the retry interval SHOULD be at
least 30 minutes; however, more sophisticated and variable strategies
will be beneficial when the SMTP client can determine the reason for
non-delivery.
Retries continue until the message is transmitted or the sender gives
up; the give-up time generally needs to be at least 4-5 days. It MAY
be appropriate to set a shorter maximum number of retries for non-
delivery notifications and equivalent error messages than for
standard messages. The parameters to the retry algorithm MUST be
configurable.
A client SHOULD keep a list of hosts it cannot reach and
corresponding connection timeouts, rather than just retrying queued
mail items.
Most servers have a retry strategie and try to deliver mail in a retry period of 2 to 5 days. Most servers will increase the retry time from e.g. 15 minutes in the beginning till every 6 hours after one day.
For exchange you can search on MessageExpirationTimeout or QueueGlitchRetryCount, QueueGlitchRetryInterval and MailboxDeliveryQueueRetryInterval.
Have fun.
Disclaimer:
The information provided in this document is intended for your information only. Lubby makes no claims to the validity of this information. Use of this information is at own risk!About the Author
Author: - Keskon GmbH & Co. KG
Wim Peeters is electronics engineer with an additional master in IT and over 30 years of experience, including time spent in support, development, consulting, training and database administration. Wim has worked with SQL Server since version 6.5. He has developed in C/C++, Java and C# on Windows and Linux. He writes knowledge base articles to solve IT problems and publishes them on the Lubby Knowledge Platform.
Latest update: 19.08.2022