Diagnosing email problems

Expertise level: Easy

There are many ways email problems can occur. Here is a list of things to look into when you encounter a problem with emails.

Error Messages

First and foremost, if you receive an error message, copy it down. This is the best way to diagnose a problem. If it says that your username and password is wrong, it is probably because that is true. You would consequently re-enter the information or reset your email password. If the error is cryptic, but there is an error number, such as the Outlook error 0X8004201A, do a quick search on the web for that error number and read up on what the issue might be.

Configuration Issues

More often than not, when you first setup an email, the problems you will encounter are due to misconfiguration. Always recheck your configurations and make sure they are accurate. Standard POP and IMAP configurations use the same incoming and outgoing mail servers such as mail.yourdomain.com. The username format is always the whole email address.

Name servers

Is your domain name pointing to the right Nameservers (DNS)? Do a whois on your domain and look if they do. Are the MX records pointing to the right server name in your DNS Zone? 

Bounce Back Emails

If you send out emails and they come back to you with an bounce back message, that means the email did not reach its destination. Here are some examples of types of messages you might encounter:

  • No such user: the email you are trying to reach does not exist. Check with the person you are trying to reach if you have the correct spelling.
  • Blacklist mention / Reputation: Look at the IP listed. Is it your server's IP or your ISP's? Contact the IP provider consequently.
  • 24, 48 or 72 hour delay and attempted delivery stopped: the server you are trying to reach did not respond. The domain might not be active. Check if the domain exists.

If you cannot figure it out with the error message received, contact our support team by opening an assistance ticket. You would have to copy the bounce back message including its full email header. To find the full email header, see this article.

Testing and Diagnostics

Here are several ways to make tests for emails.

Webmail as a Diagnostic Tool

Most of us use mail clients such as Outlook, Thunderbird, Mail, etc., for sending/receiving emails. When we encounter errors in these applications, the best way to make tests is to avoid these application and turn to the web. Your first question in diagnosing an email issue is: Can I replicate this on webmail?

Here are some tests:

  • Send an email to your own email address.
  • Send an email to an external email address (another company, hotmail, gmail, etc.).
  • Send an email from an external email address (another company, hotmail, gmail, etc.) to the one with the problem .

Note down any bad behaviour from these tests when using webmail. If you have not been able to replicate the issue you were experiencing on your computer with your mail client, the problem is not related to the server but locally to your computer settings.


When you encounter timeouts or connection issues when access to the mail server, you might want to attempt a Telnet connection from your computer. This will allow you to determine if the mail server port is blocked when you attempt to connect to it, or if the server responds.

Under Windows

  1. Open a Command Prompt (Start > Run > type in "cmd" without the quotation marks.
  2. In the terminal window type: telnet yourmailserver.com 110.
  3. Hit "Enter" on the Keyboard.
    1. If it answers "+OK Dovecot ready." You were able to establish a connection.
    2. If it times out or gives a connection error, it means the server is unreachable.
  4. Do the same test but use port 25 instead of 110 in the line so you can test the connection to the outgoing mail server instead.

Under Mac OS

The only difference in the procedure is to open a Terminal Window which is found: Applications > Utilities > Terminal

If the connection is established, the problem might be related to the server. If the connection failed, it might be due to a Firewall / Anti-virus on your computer blocking you. Consequently, your webmail tests should be positive.


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