It's often handy to dump off email to the local MTA rather than talking SMTP to a remote host directly. It's quicker, and logging is far superior to what Ubersmith provides.
This style of configuration is confirmed to work with:
Office 365 (364)
Sendgrid
Amazon SES
Ubersmith Mail container for Ubersmith 4.x
Grab a copy of cacert.pem and drop it off in /usr/local/ubersmith/conf/mail