Found this interesting stamp in an album won at an estate auction this past weekend. Don't collect Germany, so I found it kind of interesting.
AskPhil says, "Zentraler Kurierdienst: (Ger.) "Courier Mail" overprint issued in 1947 by German Democratic Republic for sealing official correspondence, used for officials, 1956-57."
Found it in Scotts under Official. Has repeated control number of 1600.
Appears to be mint, but is unfortunately stuck on one side to the album page. Why do some people have such large tongues?

Just thought I'd share.