Try these first
- Make sure your user name and password is all lowercase.
- Make sure you have created the email address in your control panel.
- Change the user name to the full email address. Example: email@example.com
Still not working?
- Change your incoming and outgoing mail servers from mail.yourdomain.com to the ip address listed in your welcome email.
Are you able to receive emails but not send?
If you can receive mail but aren't able to send this means one thing.....
Your internet provider is blocking you from using anyone's outgoing mail servers but their own. Many major ISPs are blocking outgoing emails. The reason they do this is to prevent you from using their internet connection for spamming purposes. You will still be able to send emails, but only by using your ISP's outgoing mail server. Every ISP's outgoing mail address is different, but for the most part they will be mail.yourispname.com. For example, if you had hosting with AOL.com, their outgoing mail server would look like this: mail.aol.com. If mail.yourisp.com does not work and you are still unable to send emails, you will need to call your internet service provider to find out what their outgoing mail server is.
We also have exim running on port 26 for this very reason. A possible work around is to change your outgoing mail to port 26 or 587 or 2525
Are you able to send emails but not receive?
Either your domain is out of disk space, or your e-mail address itself is out.
You will need to increase the amount of disk space to receive mail again.
Read this knowledgebase article for more information.