Below are steps you can take to troubleshoot why you cannot send/receive email from your email client. Keep in mind that this is a very linear process, so please do not skip a step.

Close and reopen email client (especially if using Outlook)
Sometimes an email client itself can cause problems preventing email from being sent or received. A quick procedure you can do is simply close and reopen the program, and then try to send and receive again. You may even want to wait 5 minutes, and then try again.

If the problem still persists, please continue to the next section.

Make sure "My server requires authentication" is checked
After making sure this is checked, make sure it is set to authenticate with the same settings as POP3. If you have a problem sending to addresses outside of your domain, or if you get a 550 Authentication is required for relay - 550 not local host error, this is the solution for those two issues.

Verify SMTP Port if the problem is with Sending
Try changing your SMTP port number from 25 to 26 in your email client.

Verify email settings are correct
If the email settings are incorrect, you will not be able to download your email. Please click on a link to watch a video tutorial for your email client settings:

Outlook 2000
Outlook 2003
Outlook Express 6.0
Eudora 7
Thunderbird 1.0
OperaMail

If the problem still persists, please continue to the next section.

Verify your website is not disabled for non-payment
If your hosting account is past due for a number of weeks, your account will be disabled. This will prevent your website from showing up, and also disable access to email. Please visit your website to ensure your site is not disabled. If you cannot view your web site, login to the billing system and take care of the outstanding invoice. Once that is done, contact us ASAP to enable your site.

If your account is not disabled, please continue to the next section.

Verify domain name is working and pointed correctly
Since email is dependent upon your domain name, if your domain name expires, or is not pointed to us, you will not be able to send/receive email. It will also prevent your website from showing up.

For instructions on how to view your domain name information, and make sure your name servers are pointed to us, please visit the following link:

View your domain whois information

If your domain name is not expired, and is correctly pointed to us, please continue to the next section.

Check for email forwarding
In order to test the email account, you will need to temporarily remove any email forwards that are on it. You will need to log into your webmail and go to your settings and look for the forwarding tab.

Once you have verified that there are no email forwards on the account, please continue to the next section.

Test the webmail account
Now that we ruled out any other possibilities, we can finally test the email account. You will need to log into webmail and perform a test send/receive message to another email address. Please make sure the test email does not go into a spam or bulk email folder. In rare circumstances, the message may be delayed up to 5 or 10 minutes. If necessary, perform a send/receive to a email address at another domain name.

Results
I am able to send/receive from webmail

Your webmail is working correctly, but most likely, your ISP is blocking you from correctly sending and receiving email.

The first step is to try changing your smtp port number from 25 to 26 in your email client.

I am able to send/receive from webmail, but I had to turn off an email forward

Your webmail is working correctly. The servers are correctly handling the email, and is delivering it to the proper location. Since the email is not appearing in the forwarded email account, the problem lies on the server the email is being forwarded to. To resolve this, you will need to contact email administrator on the forwarded domain, and have them look into it.

I am not able to send/receive from webmail - please contact support