A saas platform usually generates transactional email by calling an http api, and it is usually outgoing-only (smtp). Its not designed for sending ad hoc messag

A saas platform usually generates transactional email by calling an http api, and it is usually outgoing-only (smtp). Its not designed for sending ad hoc messages. Also, transactional email services police their usage to ensure that they are trusted as sources of legitimate bulk email. It would be hard to get away with sending much transactional email via a normal email provider without having your account shut down. In contrast. Support email is handled by people and is bidirectional and ad-hoc. Fastmail provides smtp/imap/webmail, spam filtering, mailboxes, etc. and is a good match for handling support.