SMTP Error Codes

Sending email sometimes seems impossible, lots of people have difficulty configuring their email client and even when the email client is configured correctly, they may still experience problems when sending email. With this website we hope to help fixing the problem.

The same type of problem can result in several different error messages. The reason for this is that there are many different email clients who all use their own SMTP error codes, or because the user is doing things in a different way. For example, if your email client has a "Test" button somewhere to test your settings, this may result in a different error message than just sending the email right away without testing. Also, an email may get through (it's leaving your Outbox) and everything looks fine, but then later (either right away or after a few hours or even days), you may receive a "Bounce" message from your server, notifying you about some problem.

Find out why you have problems sending email and get help solving it by using either the Help Wizard or looking up your problem manually:

SMTP Help Wizard:

Use our Help Wizard to find your exact problem and get help solving it:

Look up your problem manually:

Check the list of possible bounce message error codes (for example codes like "553" and "554 5.7.1")
Check the list of email software SMTP error codes (for example codes that look like 0x8004210B)
Find your error message in the list of per email client error messages (without an error code).