Because some Amherst College email accounts were recently phished and used to send spam, a number of email services are rejecting all emails sent from any Amherst College email address. If you get a bounce message after sending to an email address that you know is good, you've likely just bumped up against this problem.
Such blocks normally last about a week, and when IT becomes aware of such a block we try to resolve it immediately. Ultimately, however, the decision to lift such a block is out of our hands.
Consequently, if you need to send an email to a service that is blocking Amherst College emails, your only recourse in the short run may be to use a non-Amherst email account to send the message.
This reiterates the importance of keeping your Amherst account secure. If you don't know how to tell a legitimate Amherst College login page from a phony one, you need to review Don't Get Phished!
Please contact AskIT with any questions.