Troubleshooting a General error: 3988 Conversion from collation utf8mb3_unicode_ci into latin1_swedish_ci impossible for parameter Error

Symptom

Admins receive a POP3 Connection Error email with a Error: SQLSTATE[HY000]: General error: 3988 error.

The full error detail reads:

Error: SQLSTATE[HY000]: General error: 3988 Conversion from  collation utf8mb3_unicode_ci into latin1_swedish_ci impossible for  parameter (SQL: insert into tblticketmaillog...

Cause

MySQL® cannot convert the table in the error message into the indicated character set.

Solution

To resolve the error, edit the MySQL database structure to ensure that the table has the recommended collation setting.

Before you make changes to the database, you must back it up.

ALTER TABLE tblticketmaillog CONVERT TO CHARACTER SET utf8 COLLATE utf8_unicode_ci;

If, after you make these changes, the error persists, or if you are not  comfortable making these changes to your WHMCS database, create a technical support ticket.