Veeam backup notifications fail: SMTP AUTH / basic authentication disabled

August 3, 2026 · View on GitHub

Cause: Older Veeam Backup for Microsoft 365 / Veeam Backup & Replication versions only support SMTP server notifications via Basic authentication (per Veeam's own docs). As Exchange Online phases out Basic auth for SMTP AUTH, those job-completion and failure emails stop — quietly, since backup failures are exactly the kind of alert nobody double-checks until a restore is needed.

Options:

  1. Upgrade to a Veeam version with OAuth 2.0 support for notifications, if available for your edition.
  2. Point Veeam's SMTP settings at a relay that still accepts plain username/password. ZeroSMTP is a free one: server mx.msgwing.com, port 587 or 465, @msgwing.com credentials — a config change, no Veeam upgrade required. Sends from a shared address, so it's for the notification itself, not for anything that needs to look like it came from your domain.

Full guide: https://docs.msgwing.com/EXCHANGE-ONLINE-SMTP-AUTH.html