Jurawiki calls the clauses that are sometimes attached to emails Angstklauseln (anxiety clauses), and it appears the term is used by others too. They seem to be called disclaimers in English, although they aren’t just disclaimers – they sometimes tell you not to read them (rather like the test messages people send to mailing lists saying ‘Test – please do not read’.
There’s also a big collection here. Both links from AdvobLAWg via The New Joerg Times.
Jurawiki also links to another meaning of Angsklausel:
bq. Angstklausel lautet ein Vermerk, durch den der Aussteller des Wechsels seine Haftung für die Annahme und der Indossant (Aussteller eines Wechsels) seine Haftung für die Annahme und Zahlung ausschließen (so genannte sine obligo, Art.9 II WG, Art. 15 I WG).
Zahn calls this escape clause, non-liability clause, or clause permitting a party to avoid liability.
The Internet has more such collections. For instance, stupid email disclaimers, with links, including one to a site advocating the use of these disclaimers; The Register’s longest email disclaimer award. Here is more information in English.
And this is all to say nothing of fax disclaimers…