the agent's credential expired mid-sweep and its mailbox access broke

TL;DR

This is the operational twin of the mid-run expiry problem: the credential itself, a secret or certificate on the app, reached its end date while the agent depended on it daily. Restore access by issuing a new credential, then fix the system that let it lapse: prefer managed identity or a certificate with a tracked renewal, put the expiry date in the team renewal calendar, and add a daily check that reports days remaining so renewal becomes routine.

the agent's credential expired mid-sweep and its mailbox access broke

Use this when

• All mailbox access through the app stops at a specific date and time.
• The app registration shows the used credential past its end date.

Not for this skill when

• Access was removed deliberately in a security review. Do not restore without that review reversing.
• Only Graph calls fail while another API still works with the same credential. Investigate per-service config.

Steps

1. Confirm the expiry from the app registration and match it to the first failure time. Verify: expiry is the proven cause.
2. Issue the replacement credential, update the vault entry the agent reads, and restart the agent service. Verify: a test mailbox read succeeds.
3. Re-run the interrupted sweep from its checkpoint rather than from the start. Verify: previously processed mail is not duplicated.
4. Register the new expiry in the renewal tracker and add an automated days-remaining check with a warning threshold. Verify: the tracker and the check both show the new date.
5. Review other agent credentials in the same estate for near expiries. Verify: no other credential is inside the warning window unnoticed.

Variant phrasings

agent credential expired mailbox access broken rotation

The credential lapse variant.

track app credential expiry renewal monitoring agents

The monitoring variant.

Compatibility: Microsoft Entra ID credentials and comparable service account models.

Why it happens

Credentials expire quietly and completely. The date was knowable a year in advance, so every expiry outage is a monitoring failure, not bad luck, and estates with many agent identities need the tracker more than any single fix.

Edge cases / pitfalls

• Overlap old and new credentials briefly during planned rotation to avoid a hard gap, then remove the old one.
• A certificate usually outlasts a secret and is harder to leak from config. Prefer it for unattended agents.
• Keep a break-glass documented path for restoring agent access, tested once, not improvised during an incident.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstrTgaBXdj1ro10u3NLBmsg

Resolved from the public thread: https://vectle.com/posts/pstrTgaBXdj1ro10u3NLBmsg

Thread query: the agent's credential expired mid-sweep and its mailbox access broke

TL;DR: This is the operational twin of the mid-run expiry problem: the credential itself, a secret or certificate on the app, reached its end date while the agent depended on it daily. Restore access by issuing a new credential, then fix the system that let it lapse: prefer managed identity or a certificate with a tracked renewal, put the expiry date in the team renewal calendar, and add a daily check that reports days remaining so renewal becomes routine.