Encoding issue mysql
There is a Carriage Return (hex 0D) at the end of 

627269636540696775616E6573747564696F2E636F6D0D
                                            ^^


Recommend you trim emails of all "whitespace" before feeding them into your database in any way.

To confirm with your original email:

SELECT MD5('onachba@i-pcom.com');
+----------------------------------+
| MD5('onachba@i-pcom.com')        |
+----------------------------------+
| c31383bbaee83e9704fd7b0ad52581ca |
+----------------------------------+
1 row in set (0.00 sec)

SELECT MD5(CONCAT('onachba@i-pcom.com', UNHEX('0D')));
+------------------------------------------------+
| MD5(CONCAT('onachba@i-pcom.com', UNHEX('0D'))) |
+------------------------------------------------+
| c62804a6d7122356cf5f261ebf860684               |
+------------------------------------------------+
1 row in set (0.00 sec)