Microsoft is gradually phasing out basic authentication (sign-in with a username and password) for sending email through Microsoft 365. We are sharing the confirmed dates in clear terms, precisely defining the systems affected, and — most importantly — assuring you that this matter has our full attention and that we will provide a solution well before the deadline.
Key dates at a glance
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Through the end of December 2026
No change — existing configurations
continue to work. |
End of December 2026
Basic authentication disabled by default.
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After December 2026
New tenants: basic authentication unavailable by default.
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Second half of 2027
Microsoft will announce the final removal date.
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The timeline in detail
| The point to clarify: there is not yet a single, firm date for “full shutdown.” The end of December 2026 is a disable-by-default milestone — an administrator can temporarily re-enable it — and Microsoft will confirm the actual final removal date during the second half of 2027. Our recommendation is to consider the end of December 2026 as the effective deadline, because after that date basic authentication is disabled unless explicitly re-enabled. |
What is specifically affected
This change is targeted and specific. It only concerns authenticated email sending (client submission) through the Microsoft cloud using a username and password.
Affected
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Not affected
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In short: if a system sends email through smtp.office365.com (or the legacy endpoint) with a stored username and password, this is the configuration Microsoft is phasing out. The solution is to change the authentication method, not the email provider.
How Synchroteam is preparing for youThis matter has our full attention, and we are closely monitoring the steps published by Microsoft — using them to set our own internal deadlines so that a solution is ready and tested well before the December 2026 milestone.
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If you have any questions in the meantime, our team is available at support@synchroteam.com.