US Cable Support > Comcast HSI > Comcast decides to block port 25 IN and OUT with no notice.

Comcast decides to block port 25 IN and OUT with no notice.

I believe port 25 has been published on their list of blocked ports at »customer.comcast.com/help-and-su···d-ports/

A quick search reveals a blog post about it from August 1st, 2012 on their blog »corporate.comcast.com/comcast-vo···-port-25 The post mentions a slow phase in of the block which probably explains why you're noticing it months after the fact.

From the first link it seems you just need to use one of the alternate SMTP ports. Hope that helps some...

Not quite sure what you do in "remote IT" () that requires port 25, but as soon as you tell Comcast that they will come right back and either say a.) tough cookies, or b.) get a business class connection.

No, but it is very common for ISPs to require their subscribers to go through their own mail servers or use an alternate port that typically requires authentication to contact remote SMTP servers. This really isn't something new.

As was already mentioned, a business connection from Comcast does not have this restriction or a remote intermediary host or VPS can be used to perform the required tests.

reply to pclover

reply to pclover
I received this email about it, is it what you're talking about?

Dear Valued XFINITY® Internet Customer,

We care about your email security when using our network. On August 1, Comcast announced that for security reasons we will no longer support the use of port 25 for sending email from programs like Outlook or Apple Mail. It appears that one or more computers connected to your Internet account are using port 25 to send email. A port is a connection through which information flows from a program on your computer, from another computer in a network, or to your computer from the Internet, Port 25 is an unsecured port, and it is increasingly used to send spam emails through malicious computer programs called malware. These spam emails are usually sent by computers that have been infected by viruses, and as a result, most users are unaware that their computers are sending spam. By no longer supporting port 25 to send e-mail, this will help prevent your computer from sending spam without your knowledge.

What You Need To Do:

We are asking you and other impacted customers to change your email program settings to port 465, which provides more security. You will be unable to send email over port 25 once it is disabled, and you will need to update your settings to port 465 in order to continue to send email. Please click the link below for your current email software and follow the step-by-step instructions to change your settings.

reply to pclover

reply to pclover
it was in the bill mailers, I am pretty sure I have seen it here, it was notified you just ignored it or did not pay attention. So you learned the hard way like most things in life.

reply to jlivingood
It's not a matter of not being able to connect to Comcast mail servers on port 25. It's that this policy makes it impossible to connect to any other mail server on port 25. Some people do have a legitimate need to do this.

Another option would be to obtain a shell account, perhaps a freebie, on another network that does not block outbound port 25.

I don't see how running smtp tests from a residential connection are truly valid tests. What if the SMTP server had its own firewall or blacklist enabled for some of comcast's ip ranges. You should really be doing these tests from a datacenter level connection.

reply to pclover

reply to biomesh