About a week ago, my PC’s mail client (Thunderbird) started to complain that it can not login to mail.comcast.net and i could not send any email.
It continued to do so for about a couple of days. my wife’s PC was in the same condition.
When I logged into Comcast web mail, an e-mail from Comcast was waiting. It basically told me that due to suspicious activity, they blocked my port 25 to protect me being from a victim of security attack.
It also tells me how to setup a client to listen to another port. So I went ahead and setup my client to use another port. That was an end of the story for Comcast mails. (outgoing port 25)
However, I also have hMail server running for my own domain in my home server. the mail server receives emails via port 25 (incoming) this was also blocked, so I was not receiving any mails.
The my domain is served by TZO DDNS service. they also offer the service called Store and forward. The service can be a proxy receiver for mails sent to my domain, then it will forward them to my PC via port of your choice. SO I had to buy this service and configured the service to use another port (in my case 8025) to forward emails to my domain. In the htserver admin panel, I added smtp port 8025 so that the server can listen to the port.
Now the home mail server started to receive mails again.
I hope Comcast eventually removes this block after a while so that I can revert back to normal setting and unsubscribe from this Store and Forward service.