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Troubleshooting an Invalid header value detected Error during Email Importting

Symptom

After applying the 8.0.0 update, administrators may begin to receive POP3 Connection Error reports with the following detail:

Invalid header value detected

Cause

This is caused by the mailbox containing an email with non-RFC-compliant headers, which prevents the import process for completing successfully.

Solution

Please apply the 8.0.1 Maintenance Release via the Utilities > Update WHMCS page.