Within the last week, Comcast seems to have started blocking port 25 outbound from their residential internet service.
I can sort of understand why they might justify blocking it inbound as perhaps it is not within their terms of service to allow running a "server" on a residential service. I say sort of because I really don't agree with this, but whatever.
I run my own SMTP server on a hosted VPS for our business. Have done so for years. All of a sudden all of our SMTP connections from our home Comcast internet service started failing. I reconfigured the server to run SMTP on an alternate port and changed our client software at home to match and all is working again.
I suspect this is an anti-competitive measure in some respect and not merited on a technical or security basis. I imagine it would be quite a problem for someone who relied on a third party SMTP service on port 25.
Does everyone just run SMTP on an alternate port now? I know Gmail and Google's hosted email services do.
Is there any technical or security reason for Comcast to block outbound traffic on port 25 (or any outbound port really...)