Contact form passes captcha but mail relay rejects sender

Scenario

Users complete the form normally, but the message fails because the relay rejects the chosen sender address.

Recommended Resolution Path

1. Review how the form populates From and Reply-To headers.
2. Align the sender with an authorized domain or relay identity instead of user-supplied addresses.
3. Check provider logs for the exact rejection reason.
4. Document the safe mail pattern so future forms do not repeat the mistake.

Technician Notes

Document what changed, what confirmed the fix, and whether the issue points to a broader standards gap worth addressing for the client.