Last of the Royal Mail Ships retired

The old RMS St. Helena has been retired due to opening of an airport on the island of St. Helena.
She will now serve as a floating armoury in the Gulf of Oman:

RMS Queen Mary 2 doesn’t count? Actually, even QM2 isn’t the last:

In recent years the shift to air transport for mail has left only three ships with the right to the prefix or its variations: RMS Segwun, which serves as a passenger vessel in Gravenhurst, Ontario, Canada; RMV Scillonian III, which serves the Isles of Scilly; and RMS Queen Mary 2. QM2 was conferred “RMS” by Royal Mail when she entered service in 2004 on the Southampton to New York route as a gesture to Cunard’s history.

I’m guessing he means actual working mail ship.