Transactional & SMTP
SMTP Authentication Methods Explained
SMTP AUTH proves your client may send; SPF and DKIM prove your message is genuine. This guide compares PLAIN, LOGIN, CRAM-MD5, SCRAM, and XOAUTH2, walks the handshake step by step, maps ports to encryption modes, and decodes the errors you will actually hit.
Sep 16, 20269 min read