A large number of Internet Service Providers (ISPs) have started to block access to SMTP servers that do not reside on their network. This is their way of attempting to reduce spam on the internet, as they feel that they have more control if they can force their clients to use their internal email servers.
To do this, they block connections to port 25, which is the standard SMTP port on servers. If your ISP does this, you may receive an error message similar to:
"Unable to connect to your outgoing SMTP email server"
To test connection to port 25, please complete the following steps:
Mac:
1) Open the Terminal program.
2) In the terminal window that appears, type:
telnet mail.domain.com 25
replacing domain.com with your domain name on our server.
Windows:
1) Click Start, then Run, and type:
cmd
Then click OK.
2) In the DOS window that appears, type:
telnet mail.domain.com 25
replacing domain.com with your domain name on our server.
If you receive a response from Exim similar to the following, the connection was successful, and port 25 does not appear to be blocked:
220-servername.kualo.com ESMTP Exim 4.43 #0 Thu, 11 Nov 2004 16:19:41 +0000
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.
If the connection could not be made, try again using port 587 instead of port 25. If a connection is made successfully this time, you have just proved that your ISP is blocking outgoing SMTP connections.
To use port 587 for your outgoing emails, you will need to make some changes in your email client. These are generally made in the advanced settings section of your account configuration. You will see that by default, POP3 is configured for port 110, and SMTP for 25. Simply change the SMTP value to 587, and attempt to send emails.
If you still experience issues after following these steps, please do not hesitate to contact our support team via my.kualo.com.
