I know it’s frustrating when you can’t send a mail. Fixing email delivery problem to our server management customer is one of the top 3 things.
1. Bad Passwords
Many support tickets turn out to be password issues. We reset the password and then the emails stats flowing.
Browsers like Firefox and other applications add spaces to copy paste passwords. Next time you copy the password, copy it in notepad to make sure there are no passwords. This is one of the quickest ways to verify the password.
2. Mail Server (SMTP) is Offline
In WHM and Pesky C-Panels, mail servers crash often. restart the services from the control panel, it will work just fine.
A connection error from your email client will be returned to you.
The clue in this message is “mail2.rackaid.com is unknown.”
Make sure there is no typo’s in the hostname. These are the common issues. Check your DNS, if your hostname is correct.
3. ISP Blocking Port 25
Your ISP is blocking port 25.Many ISP’s use their own SMTP server even if you have your own. This is a common issue for support.
You can test if port 25 is blocked by using a telnet client to connect to port 25. For example:
|[j***h@office ~]$ telnet mail.r***id.com 25
This test just sits there until it times out. If I use SSH to connect to my server then test the port, it works. I see the SMTP banner.
220 mail.ra***d.com ESMTP Postfix
If you see the STMP banner, then your ISP (or firewall) is blocking the connection.
One tip is to use port 587. Many ISPs do not block this port:
|[je**h@o***e ~]$ telnet mail.r****id.com 587
Connected to mail.ra***d.com.
Escape character is ‘^]’.
220 mail.r***id.com ESMTP Postfix
Contact your network provider if that still fails. On most business accounts, the will permit port 25. Increasingly, residential accounts are permanently blocked.
4. SMTP Authentication
Some email systems like Outlook use an authentication method which is older called POP before SMTP. You just need to configure your POP3 or IMAP setting. This method works perfectly fine, many email system still approves this as an option.
But now a day, new policies are set in place which forces you to use SMTP authentication.
For example, pesky c-panel enabled POP by default for years, but in newer versions of pesky, this method is now disabled. If you are seeing this change, email accounts can no longer send emails.
The server often rejects them when there are emails with relay denied, server often rejects them. This means SMTP authentication is not enabled.
If you get a relay denied error and your password is correct, then SMTP authentications are likely not correct.
Often, email users with this issue can receive but cannot send email.