IMAP
From CafeWiki
Courier IMAP is used to manage the IMAP stores for all of the users on the mailserver.
Installation
Installation of courier IMAP, in place of the default dovecot for ubuntu, is covered under the Postfix page as it is best done immediately after building the mailserver when configuring Postfix.
Configuration
Connection limit issues
As a result of using one computer to check all of the family email accounts, the mail.err log on the mail server was always getting connection limit exceeded errors from that family computer. For example,
May 27 19:09:00 server-name imapd-ssl: Maximum connection limit reached for ::ffff:123.321.123.1 May 27 19:10:15 server-name imapd-ssl: last message repeated 17 times
It turns out that the likely cause is that the one mail program is checking all of the IMAP directories for 6 different mail accounts all at once. Two solution spring to mind: configure the mail app to stagger the checking for new mail or increase the IMAP connection limit.
This German webpage turned out to have the answer to how to implement the second solution:
- edit the imap config file
nano /etc/courier/imapd
- find the parameters for MAXDEAMONS and MAXPERIP and try larger values. I bumped the values for each by 50% (MAXDEAMONS from 40 to 60 and MAXPERIP from 20 to 30)
After a week or so, the number of connection limit errors was way down to only 3 log entries, all of which seem to have been due to manually checking for email while waiting for something to arrive.
