[CentOS] Mail has quit working

Tue Jul 24 03:22:23 UTC 2018
Peter <peter at pajamian.dhs.org>

On 24/07/18 13:46, Nataraj wrote:
> Simply telnet to mailserver on port 25 and type what I've shown,

This is pointless because he's complaining about cron and system emails
which use the sendmail command are submitted through the pickup service,
not port 25/smtp (in fact, if you're submitting any mail via port 25
you're doing it wrong but that's another discussion).

TE Dukes:

Please do the following (lines that start with # should be run as root,
lines that start with $ should be run as a local user):

Install the mail command which is an easy interface to the sendmail
command and thus the pickup service.

# yum install mailx
# tail  -n0 -f /var/log/maillog

...then in another window (replace someuser at example.com with your own
email address):

$ mail -s 'Test Email' someuser at example.com <<< "This is a test"

... wait a minute for postfix to have a chance to process and send the
message, then break out of the tail command and copy/paste the output
into your reply.

Then also copy and paste the output of the following:

$ postconf -nf; postconf -Mf

If I need any more info after that I'll let you know.