Microsoft has announced that it will permanently retire Microsoft SMTP Basic Authentication (Client Submission) before the end of December 2026. This change may affect email delivery from your Dimensions or FocalPoint system if it is currently configured to use Basic Auth.
For more information please refer to Source, Microsoft article.
Microsoft’s Retirement Timeline
Now to December 2026: SMTP AUTH Basic Authentication behavior remains unchanged.
End of December 2026: SMTP AUTH Basic Authentication will be disabled by default for existing tenants. Administrators will still be able to enable it if needed.
New tenants created after December 2026: SMTP AUTH Basic Authentication will be unavailable by default. OAuth will be the supported authentication method.
Second half of 2027: Microsoft will announce the final removal date for SMTP AUTH Basic Authentication.
In summary, all SMTP Basic Auth usage must be fully migrated to OAuth-based Modern Authentication before the end of December, 2026.
How to Determine if You’re Using SMTP Basic Auth
To ensure an uninterrupted email service, we recommend verifying your current authentication method as soon as possible. Here are several ways to check:
Exchange Admin Center – SMTP Auth Clients Report.
Microsoft has updated this report to display whether each SMTP submission uses Basic Auth or OAuth. Use it to identify any mailboxes or applications using Basic Auth.
Azure AD Sign-in Logs
In Azure Active Directory → Sign-ins, filter by Client App = SMTP. Entries showing Legacy Authentication indicate Basic Auth.
Modern Authentication indicates OAuth and will continue to work after the deprecation.
Exchange Online PowerShell
Run the following checks for each mailbox:
Get-CASMailbox - Identity [email protected] | Select SmtpClientAuthenticationDisabled
False = SMTP AUTH enabled (Basic Auth possible)
True = Basic Auth disabled
Review authentication policies:
Get-AuthenticationPolicy | Format-List Name, AllowBasicAuthSMTP
Get-User -Identity [email protected] | Format-List AuthenticationPolicy
Review Application or Device SMTP Settings.
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Guidance for Dimensions users
Click System, then Options, then click System Control Options, then System Format, and finally click System Email Defaults.
If the SMTP setup uses a username and password to connect to Office 365 (port 587 or 25), this likely indicates Basic Auth.
Guidance for FocalPoint users
Click System Options, then Global Options, then click General Options and finally click Email.
If the SMTP setup uses username + password without OAuth tokens, this likely indicates Basic Auth.
Next Steps
If you determine that any of your systems are still using SMTP Basic Authentication, you will need to transition to OAuth/Modern Authentication before the end of December 2026.
If you are using SMTP Basic Authentication, please declare by completing this form and we will be in touch to complete the next steps.
If you have questions or need assistance evaluating your configuration, please contact our support team.