Microsoft office 365
ARC uses this email service. They require TLS encryption using stunnel.exe.
Users on our hosted Profits Plus servers can get away without having to do SMTP authentication or encryption by using this web page: http://technet.microsoft.com/en-us/library/dn554323%28v=exchg.150%29.aspx Use the "SMTP Relay" option to setup a static IP address to use port 25, no TLS, no Authentication. Caution: Office 365 says they don't allow bulk email and our statement program e-delivery feature behaves exactly like a bulk email or newsletter program.
Here is a sample email you can use to help a customer decide how to implement Office 365 email. You can modify the text and use it for a customer going to gmail too (they have the same issues).
Gmail
Dynamic uses this. TLS required, SMTP relay not allowed, you must prompt for sender's email password for authentication. Here is a sample email you can use to help a customer decide how to implement gmail. It is written assuming Office 365 so you'll have to change that to say "gmail.com"
GoDaddy
MV Software uses this. No encryption on port 80. SMTP authentication required. As long as the SMTP authentication is correct you can send emails "from" any domain. For instance, I have loaned my personal email account nmiller@mvsalliance.com to customers and used my credentials as their SMTP authentication and the user can enter their own "from" addresses which of course are not in the mvsalliance.com domain.
Yahoo
stunnel is required but it doesn't work with the free version of Yahoo email. Only the "plus" yahoo email can be used with stunnel. There is a monthly fee for the "Plus" yahoo email.