Saturday, March 27, 2010

Why you can't connect to the SMTP relay server

We often get inquiries from customers telling us that they're unable to relay emails through Here is a list of the most common reasons why it doesn't work.
  1. Your Internet Service Provider (ISP) is blocking access to external email servers. By default, the SMTP server listens on port 25, and many ISPs block connections on port 25 in order to prevent you from emailing through an external email server. For this reason, our SMTP server also listens on port 587 and 2525. You can also connect securely over SSL/TLS on port 465. You can test connectivity from a Command Prompt by typing:

    telnet 25

    Successfully connecting to

    If that doesn't work, try:

    telnet 2525

    You should get a response from the server as shown in the screenshot above.
  2. You haven't setup a proper authentication method. In order to relay emails through, you must login to your account, go to Settings --> SMTP Relay, and authenticate either by IP Address or Username/Password.
  3. You are connecting to the wrong server. We've had customers attempt to connect to,, and, all of which are incorrect. The correct server is
  4. You are manually inputting SMTP commands in order to complete a SMTP transaction. Unfortunately, unless you manually input the data for a proper and well-formed email message, including a Subject and a Message, our system will discard it.
How do you know if your email goes through the relay server properly? You will see your email almost instantly in Reporting after you send it.