SMTP AUTH is disabled by default for Microsoft 365 organizations created after January 2020 and must be enabled per mailbox for client SMTP submission. Basic-auth SMTP submission is incompatible with Microsoft Entra ID security defaults.
Checked 2026-10-02
- Vendor
- Microsoft
- Product
- Exchange Online
- Subsystem
- SMTP client submission
- Deployment
- multi-tenant
- Region
- not restricted
- Release range
- current as of 2026-10-02
- Checked
- 2026-10-02
Sources
- How to set up a multifunction device or application to send email using Microsoft 365 or Office 365 — Microsoft · tier 2 current vendor documentation · Client SMTP submission > Tip (SMTP AUTH enabled for the designated mailbox); security defaults sentence
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting Unity Connection voicemail-to-email and notifications: source note unity-connection-notification-troubleshooting-m365-smtpauth. WarmTransfer. https://warmtransfer.net/knowledge/claims/unity-connection-notification-troubleshooting-m365-smtpauth
BibTeX
@misc{warmtransfer-claim-unity-connection-notification-troubleshooting-m365-smtpauth,
title = {Troubleshooting Unity Connection voicemail-to-email and notifications: source note unity-connection-notification-troubleshooting-m365-smtpauth},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/unity-connection-notification-troubleshooting-m365-smtpauth},
note = {Source note unity-connection-notification-troubleshooting-m365-smtpauth, checked 2026-10-02}
}