So occasionally, Comcast will block inbound TCP port 25, but if you call in and/or IM one of the mods on this forum, they can have that block removed. However, I don't know of any circumstance where they block port 465... here is the official list of blocked ports:
So you might have some firewall issues on your end. Mind telling us more about your network? (which model of gateway, which routers/firewalls you have if any, what sort of SMTP server, etc.)
Had Comcast business account and mail was working fine with a Comcast cable modem. Moved business account home where I was using the Motorola SB6121 cable modem. Now mail is not working...everything behind cable modem is idenitcal as previous.
Hello HaoT and welcome,
You should register your Business Class Portal account and use you DNS info mail addresses provided within that link.