Fiorenzo Longhi reported on page 22 of the Spring08 issue of the ZEPPELIN POST JOURNAL about the lowest known Greek registration number for zeppelin mail on the 1933 LZ-127 Graf Zeppelin Rome Flight, which is 7025.
The latest Heinrich Köhler auction (Wiesbaden, Tuesday September 15, 2009, 2 p.m.) presents with lot 1959 an even lower number: 7013.
Source: www.eZEPtalk.de
Direct link: http://www.ezeptalk.de/viewtopic.php?f=34&t=163&p=558#p558