POSTFIX is installed automatically by the RKHUNTER installation unless an option is taken:
sudo apt-get -y --no-install-recommends install rkhunter
reference: https://hostpresto.com/community/tutorials/how-to-install-and-use-rkhunter-on-ubuntu-14-04/
POSTFIX can be tested by using:
echo “it works!” | mail -s “testing” your@e-mail.address.elsewhere
https://www.linode.com/community/questions/4242/how-do-i-check-if-postfix-setup-correctly
Sending a test email to my gmail account resulted in a rejected email response due to failing one or more of several possible checks designed to protect gmail accounts from spam:
The redirection email suggests the following reference to diagnose what rejection criteria was triggered:
https://support.google.com/mail/answer/81126#authentication
The first rejection criteria was the lack of reverse DNS. This could be checked on this handy website:
https://www.debouncer.com/reverse-dns-check?ip=64.225.13.42
This check shows that reverse-DNS is not active for www.seebylooking.com
Researching how to enable reverse-DNS, there were many posts and articles. Some directed users to enable a “PTR” record of domain host service.
Other posts directed users to make modifications on the server itself – in my case, digital ocean.com.
https://www.digitalocean.com/community/questions/how-do-i-create-a-reverse-dns-ptr-record
This post also noted changes to be made in the /etc/hosts and /etc/hostname files
I’ve done one:
This one needs figuring out… (note the reference that the file is in two places…)
Here’s a link to a tutorial on using two third party mail facilities:
https://www.wpbeginner.com/wp-tutorials/how-to-fix-wordpress-not-sending-email-issue/
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