For client SMTP submission to Exchange Online, Microsoft specifies smart host smtp.office365.com (not an IP address), TCP 587 (recommended) or 25, STARTTLS with TLS 1.2 or 1.3, and the credentials of a licensed mailbox.
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 > Set up client SMTP submission (settings table)
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting Unity Connection voicemail-to-email and notifications: source note unity-connection-notification-troubleshooting-m365-smtp-auth. WarmTransfer. https://warmtransfer.net/knowledge/claims/unity-connection-notification-troubleshooting-m365-smtp-auth
BibTeX
@misc{warmtransfer-claim-unity-connection-notification-troubleshooting-m365-smtp-auth,
title = {Troubleshooting Unity Connection voicemail-to-email and notifications: source note unity-connection-notification-troubleshooting-m365-smtp-auth},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/unity-connection-notification-troubleshooting-m365-smtp-auth},
note = {Source note unity-connection-notification-troubleshooting-m365-smtp-auth, checked 2026-10-02}
}