How to resolve Send SMTP Mail Timeout Error Caused by CRL Validation in SendGrid?
Issue description:
When attempting to send emails through SendGrid using the Send SMTP Mail activity, the operation fails with a timeout error. The issue occurs when CRL validation is enforced, which requires checking the validity of the SSL certificate against external revocation lists.
Resolution:
The proposed solution is to whitelist the GoDaddy OCSP/CRL endpoints from the network side to allow CRL validation.
This ensures that outbound HTTP requests to the required certificate validation servers are permitted.
Endpoints to whitelist:
- http://ocsp.godaddy.com/
- http://crl.godaddy.com/gdroot-g2.crl
- http://crl.godaddy.com/gdroot.crl
⚠️ Note: These addresses may differ depending on the customer’s environment. To identify the correct CRL endpoint:
- Use Fiddler to capture the trace; failed requests will appear as a 502 Connection Failed.
Also ask the customer to test the connection with PowerShell: Invoke-WebRequest -Uri "http://crl.godaddy.com/gdroot-g2.crl"
If access is successful, CRL validation will complete, and the timeout error should be resolved.