If emails are getting delayed, its better to inspect postfix mail queues, coupled with postfix mail log.
Postfix maintains different queues for different purpose.active and deferred queues are of our interest.
Ideally, we should never have a mail in deferred queue.
qshape command will show shape of active mail queue by default. Ideally it should be as close as to empty since postfix sends email instantly!
qshapePlugin Name: HTTP TRACE / TRACK Methods Allowed
To turn off track and trace methods globally on the server add the following line:
vim /etc/httpd/conf/httpd.conf
TraceEnable Off
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To create a banner so that whenever a user logs into a system will see some default text, you can couple of options
1. put the default text into /etc/motd
2. type echo “<the text you want to display>” into /etc/profile
3. type echo “<the text you want to display>” into user home .profile file. Read More
TCP wrapper based access List Rules can be included in the two files
/etc/hosts.allow and
/etc/hosts.deny . Read More