NetFixerFrom my cold dead handsPremiumReviews:
reply to NormanS
Re: Is outbound port 25 blocked/filtered Your port 25 summary is true except that it only applies to residential accounts. Business class accounts are not supposed to have port 25 blocking. The OP appears to be a business class customer since both of the IP addresses point to webmail.attbizclassemail.com (which I would assume from the hostname implies an email site for business class customers).
FWIW, I can get outbound port 25 connectivity to the OP's first IP address (126.96.36.199) from the two AT&T business class connections to which I just established a VPN tunnel (as well as from my normal Comcast Busineess Class connection).
OTOH, the OP's second IP address (188.8.131.52) does not respond to port 25 requests at all It does respond to port 110, which tells me that it is probably a POP3 server only, and does not have SMTP capabilities.
We can never have enough of nature.
We need to witness our own limits transgressed, and some life pasturing freely where we never wander.