GMAIL 
In TSS XP, under Application Settings / Email, configure the settings as specified below:
NOTE: Also try port 587 if it fails to connect on port 25.
Yahoo
Make sure the 'reply address' is the same as your 'user name'.
If you want to use a different reply address then your account you must verify the alternate address with Yahoo. Please visit Verify Yahoo Email to verify your email address.
Verizon 
Known issue with Verizon, see below error message.
"550 5.7.1 The message you attempted to send was determined to be spam. Please visit http://www.verizon.net/spamfaq for more information."
Verizon scans all email sent or receives and automatically blocks ones it thinks are spam based on its contents. You can send the email to them at spamdetector.update@verizon.net and they will review it to see if they can un-block it.
GoDaddy
Known issues with authentication errors, they don't allow you to send emails from alias addresses, the sender must be the email account your connecting with.