Verizon blocked Port 25 no smtp

Submitted by lueung on Tue, 05/11/2010 - 14:48

Verizon just started blocking Port 25 and I can no longer send outbound SMTP mail. from home using Outlook. Is there a work around for this?

Status: 
Closed (fixed)

Comments

Submitted by andreychek on Tue, 05/11/2010 - 15:26

You can enable SMTPS and/or Submission, which would enable you to send mail using an alternate port.

To do that, edit /etc/postfix/master.cf, and uncomment the lines near the top related to "smtps" and "submission", then restart Postfix using "/etc/init.d/postfix restart".

After that, you can setup Outlook to use SSL or TLS on ports 465 or 587 for outgoing emails.

Submitted by lueung on Tue, 05/11/2010 - 16:38

I tried that it didn't work. Could you take a look?

Submitted by andreychek on Tue, 05/11/2010 - 16:48

Well, when you say it didn't work, what went wrong exactly -- did you get any error messages?

After enabling SMTPS in the master.cf file -- I might suggest starting by configuring Outlook to use SMTPS on port 465 using SSL, as that tends to be the simplest to get working.

Submitted by lueung on Tue, 05/11/2010 - 16:59

Send test e-mail message: The operation timed out waiting for a response from the sending (SMTP) server. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).

Tried all your suggestions. No luck.

Submitted by lueung on Tue, 05/11/2010 - 20:53

Finally got it working by using this instead.

Mod Begin

smtp inet n - n - - smtpd 2525 inet n - n - - smtpd

Mod End

(The above is not displaying correctly) Will this cause any potential problems?

Submitted by andreychek on Tue, 05/11/2010 - 22:20

It's no problem to add an additional port such as 2525 like you did, that should work just fine.

However, using SMTPS on port 465 should work well too. Based on the error you mentioned above, it sounds like it wasn't listening for requests on that port. I'd be happy to log in and verify that SMTPS and Submission are enabled in your master.cf file correctly, and that saslauthd is working.

If you'd like me to do that, you can either enable Remote Support using the Support Module, or you can simply email your root login information to eric@virtualmin.com.

Submitted by andreychek on Tue, 05/11/2010 - 23:01

Okay, using the login information you provided, I setup SMTPS and Submission on your server.

That should enable authenticated connections on port 465 and 587.

Try configuring Outlook to connect on port 465 using SSL for Outgoing SMTP connections, and see if that works for you.

Submitted by lueung on Wed, 05/12/2010 - 00:16

I've tested using the suggested ports and no go. It seems that uncommenting the the smtps and submissions section results in a timeout for 465 and 587. Can't see why it wouldn't work while the following does. Now it's got me curious.

smtp inet n - n - - smtpd 2525 inet n - n - - smtpd

Verizon just started blocking port 25 today so I am sure you guys will get more queries on this.

Submitted by andreychek on Wed, 05/12/2010 - 08:39

Yeah, this already does come up a fair bit, a lot of ISP's block port 25.

However, I've never heard of an ISP blocking outgoing port 465 or 587... and since I'm able to connect to those ports on your server, it's possible they're blocked for you.

I'm glad port 2525 works for you though.

An alternative is to use your local ISP as a mail relay, but to use your server to actually retrieve any email via POP or IMAP.

Submitted by lueung on Wed, 05/12/2010 - 09:56

Seems that way. Verizon's suggested solution is to get a static IP or a business account and pay much more $$ just to access outbound mail from home. That's not a solution. Interesting to see how this plays out.