If your emails have stopped appearing in ClientSuccess engagements, your Microsoft 365 connection has most likely lost authorization. This usually happens after a Microsoft password change or a periodic token expiry. The fix is a quick disconnect-and-reconnect of your email authentication.

Symptoms

New emails to/from your contacts are no longer showing up in the Engagements module.
Sync stopped around the time you changed your Microsoft 365 password or IT rotated credentials.
You see an authentication, token, or "reconnect" prompt on the Email Authentication screen.

Cause

ClientSuccess connects to Microsoft 365 through a secure OAuth token. When your Microsoft password changes — or the token reaches its expiry — that token is invalidated and email syncing pauses until you re-authorize. Re-authenticating issues a fresh token and resumes the sync.

Solution

Option 1 — Re-authenticate (disconnect → reconnect)

This fixes the large majority of "email stopped syncing" cases. Tip: do this during a low-activity window, since syncing pauses briefly while you're disconnected.

Open My Settings. In the top-right user/profile menu, go to My Settings.
Open the Email Authentication tab. This section manages the connection between ClientSuccess and your Microsoft account.
Disconnect the current Microsoft 365 connection. Locate the active Microsoft 365 connection and click Disconnect. This clears the old, expired credentials. Email syncing pauses while disconnected.
Reconnect. The Connect Microsoft365 option will reappear. Click it and follow the Microsoft OAuth prompts to re-authorize your account.

Verify it worked: after reconnecting, ClientSuccess automatically pulls in emails from the past 24 hours and continues syncing every hour. Send/receive a test email with a known contact and confirm it appears in their Engagement timeline within ~1 hour.

Option 2 — If the reconnect fails or won't authorize

Two-step verification / app password. If your org enforces MFA, you may need an app password (requires two-step verification enabled on your Microsoft account) when prompted for credentials.
Microsoft permission scopes. The integration needs these Microsoft Graph scopes approved (an M365 admin may need to grant consent): openid, profile, email, User.Read, offline_access, Mail.Read, Mail.Send.
Admin consent blocked. If your tenant blocks third-party apps by default, your Microsoft 365 administrator may need to approve ClientSuccess before the connection will hold.

Recovering emails missed while sync was down

Reconnecting only back-fills the previous 24 hours. If you were disconnected longer and need older emails imported, email support@clientsuccess.com with a specific date range (e.g., "past two weeks") and the team can run a back-sync for you.

Still missing only specific emails?

If sync is working but individual emails aren't appearing, it's usually a matching/rules issue rather than authentication. See Troubleshooting Missing Emails — common causes are alias/secondary sender addresses and the email-sync rules (the message must be to/from a contact that already exists in ClientSuccess, and not in drafts/spam/trash).

Prevention

Re-authenticate right after any Microsoft password change — the #1 trigger for dropped sync.
If IT rotates credentials on a schedule, add a reconnect step to that runbook.

Still having issues?

Contact support@clientsuccess.com with your account name, the affected user's email, and roughly when sync stopped. For specific missing messages, attach the Internet Headers / Message Source (Outlook/Office 365) for one example email.