[2024-feb-29] Sad news: Eric Layton aka Nocturnal Slacker aka vtel57 passed away on Feb 26th, shortly after hospitalization. He was one of our Wiki's most prominent admins. He will be missed.

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I assume sendmail should be stopped and disabled with

. /etc/rc.d/rc.sendmail stop
chmod -x /etc/rc.d/rc.sendmail

before postfix is installed, as postfix has its own sendmail executable to provide functionality for other programs which expect to use sendmail. — Tim Dickson 2015/09/14 14:13

Mistake in the virtual mailbox configuration:

To use mysql on a remote server, I had to replace “host” with “hosts” in the virtual mailbox configurations–postfix defaults to 'localhost' anyways, which is why this error goes undetected, but want something besides the default value, and this error must be fixed as thus:

emacs /etc/postfix/mysql-virtual-mailbox-domains.cf

# Enter the following lines #
user= mailuser
password = {your mailuser password}
hosts = {mysql server's ip address}
dbname = mailserver
query = SELECT 1 FROM virtual_domains WHERE name='%s'

(the revision is the “s” that was added to “host”) – slac.in.the.box

 talk:howtos:network_services:postfix_dovecot_mysql:postfix ()