Compliance-deadline phishing exploiting Microsoft's real April 30 2026 SMTP AUTH / Basic Authentication sunset. Email uses the legitimate deadline for urgency — "basic auth retiring," "SMTP AUTH deadline," "app password will stop working," "IDCRL retirement" — plus a panic CTA ("migrate now," "re-authenticate now," "avoid service disruption," "mailbox will be suspended") pointing at a non-Microsoft URL that harvests M365 credentials. Microsoft Tech Community + Learn docs are the authoritative deadline reference; historical precedent: 2022 first-wave basic-auth deprecation spawned dozens of phishing campaigns per Sophos — April 2026 deadline replays this exactly

Compliance-deadline phishing that exploits the real Microsoft SMTP AUTH / Basic Authentication sunset on April 30 2026 (documented in Microsoft Tech Community and Microsoft Learn deprecation posts). The attacker cites the genuine deadline to create urgency: "basic authentication is being deprecated," "SMTP AUTH deadline April 30," "your app password will stop working," "legacy SharePoint authentication IDCRL is retiring May 1." The email then pushes a panic CTA — "migrate now," "re-authenticate now to avoid service disruption," "your mailbox will be suspended" — pointing at a non-Microsoft URL that looks like an O365 sign-in page but harvests credentials. The real Microsoft 2022 first-wave basic-auth deprecation spawned dozens of phishing campaigns per Sophos and Microsoft's own threat reports; the April 2026 deadline is expected to replay that wave, with tens of millions of users and every IT admin in the world in-play. Distinct from generic MS365 credential phishing because it rides on a REAL policy change with a REAL deadline — users who know the deadline is real are primed to click. Legit Microsoft communications link exclusively to microsoft.com / learn.microsoft.com / microsoftonline.com / office.com. Any "migrate now to avoid mailbox suspension" email whose link target is a non-Microsoft host is, by construction, a phish — there is no legitimate third-party migration portal.