Monday night I was out with a few Techies and the conversation got around to “how most ISPs block port 25”, “hosting companies”, and “SPAM”.
Monday night I mentioned how there was another port that you could use to send email and about how to keep your site off blacklists. As many of you know I’m not an Exchange person but I agreed to Blog about it. Today I will talk about the alternate port that can be used with some hosting companies to send mail and not “relay” email via your ISP.
As everyone knows port 25 is SMTP, however there is a second port 587 (email message submission) and while researching this blog post I also found out about port 465 (SMTP over SSL) https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
If you have a hosted web site, then you would have to use your ISP and “relay” your email through them. But in order for everyone to reply to your hosted email address you need to setup your “reply to” and “Display Name” setting to your hosted web site email address. This works but it also mean that more SPAM checkers will flag your message as SPAM.
To change this so that your hosting company and therefore your SMTP address is sending out your email thereby reducing the chances that your email is flagged a SPAM.
Test if your hosting company will allow email sent via port 587
– Open a DOS prompt
– Telnet <SMTP address> 587
– You should see something like this “220 <SMTP address> ESMTP Postfix, (smtp3)”
If you do make the following changes to Outlook or whatever email reader you are using and now all of your email will be sent via your SMTP server and thereby reducing your chance that your email is flagged as SPAM.