I use "Exim version 4.63 #1 built 30-Mar-2011 12:18:10" (from: exim -bV)
on several servers. It is standard software on Centos 5.6 (the reliable
Red Hat clone).
Recently a free-standing server disappeared after its Exim configuration
was changed and before a Save of the changes was done :-(
The old version of the configuration contained:
acl_check_rcpt:
accept hosts = m1.xxx.com : m2.xxx.com : m3.xxx.com : m4.xxx.com : \
m5.xxx.com : m6.xxx.com
which appeared valid. But mail sent by a valid host, m2.xxx.com, was not
being identified as coming from m2.xxx.com and then failing the
subsequent checks.
Eventually I discovered that the first host name, m1.xxx.com, did not
have a valid DNS entry. Consequently Exim ignored/rejected without
warning all the other valid host names which had valid DNS entries.
Regards,
Paul.
