How do I check to see if my ISP is blocking port 25 (SMTP) for outgoing email?

 

You can run a simple test to see if your ISP is blocking port 25. Open a command prompt for windows or Terminal.app for OS X and type in the commands below.

telnet yourdomain.com 25

 

If your ISP is blocking port 25 you will not get a response back. However if it isn't blocking port 25 you will see an output similar to the one below.

[user@host:~]$ telnet yourdomain.com 25
Trying xxx.xxx.xxx.xxx...
Connected to yourdomain.com.
Escape character is '^]'.
220-host.domain.com ESMTP Exim 4.69 #1 Mon, 07 Jul 2008 00:22:59 -0600
220-We do not authorize the use of this system to transport unsolicited, 
220 and/or bulk e-mail.





Please keep in mind that you should be using a secure (SSL) connections for Outgoing SMTP and Incoming IMAP or POP3.

Outgoing SMTP Port 587, Incoming IMAP Port 143 and for Incoming POP3 port 110.


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