SMTP (Simple Mail Transfer Protocol) is used to send e-mail messages from one server to another.

What port should I use for SMTP?

The most commonly used SMTP port is port 25, however some internet service providers will block this port. Therefore, as an alternative we suggest using port 587. If you have configured your email client to use SSL settings then we recommend that you use port 465.

Why am I getting an authentication error when sending out mail?

If you get an authentication error when sending via SMTP this usually means one of three things:

1. Your user name (normally your e-mail address) has been entered incorrectly in your email client's outgoing settings
2. Your password has been entered incorrectly in your email client's outgoing settings
3. SMTP authentication has not been enabled in your email client

All three of these are required in order for you to use SMTP.