If you are using Postfix, make sure that you are not trying to send from a send-only SMTP server:
How to Install and Configure Postfix as a Send-Only SMTP Server on Ubuntu 16.04
sudo nano /etc/postfix/main.cf
Scroll down to make sure that the following parameters are set to the values below (substituting your own values where appropriate):
inet_interfaces = all
mydestination = $myhostname, custom-website.com, localhost.com, , localhost
sudo systemctl restart postfix
If you are integrating your email with a commercial client such as Outlook or Gmail, make sure that your are testing for incoming mail from another commercial email address.
For example, do not test for incoming email from
Instead, send from a tried-and-true email service like
If the mail reaches your server, then you probably have a problem with outgoing email from
custom-website.com, rather than incoming mail.
If all else fails, make sure that the incoming email did not end up in spam.
Also, make sure that your MX records are set up properly. Most hosting providers have guides to help you set these specifications up properly. Here are some general instructions:
General Instructions to change the MX records