Can't Switch from Port 25 to Port 587

Comcast has blocked my outgoing e-mail by requiring a port change and nothing its tech rep can suggest will enable me to switch Evolution from 25 to 587.

Background: A radical-Leftist political writer and blogger in the increasingly Nazified United States, my e-mail is frequently subject to malicious spam reports which Comcast, my server, always accepts as truth and blocks my outgoing e-mail, something that has happened at least a half-dozen times since I began criticizing the Obama Administration for its serial betrayals of pre-election promises.

Usually the problem is solved by an irate telephone call to Comcast tech support, but tonight it reached a new low with Comcast's decision to shift me from port 25 to port 587 -- something seemingly impossible with Evolution as the Comcast tech rep and I were at this increasingly infuriating chore for more than three hours with no joy.

Her advice (and this is the only thing I know as I am NOT say again NOT a Nurd; I have Ubuntu primarily for its Gimp photo software and am otherwise a total ignoramus about computers) was as follows:

In Evolution>Edit>Preferences>Mail Accounts>Edit>Sending Mail, settings as follows:

Server type: STMP
Server Configuration:
Server: stmp.comcast.net:587
server requires authentication (checked)
Security:
use secure connection: SSL encription
Authentication:
type: plain
user name: lorenbliss ("everything in e-mail address preceding @ Comcast")
remember password (checked)

I hope this can be solved but, frankly, doubt that it can as I have repeatedly done everything the tech support person instructed (including several reboots), all to no avail. Meanwhile I am effectively shut down, limited to Comcast's own e-mail which (unless I am willing to be ripped off something like $150 per month for its business service) will not allow list mailings nor even the construction of mailing lists. So much for net neutrality in the land of ultimate capitalist malevolence. In any case please help if possible.

Thank you,
Loren Bliss