>We've searched Lotus' web site and come across a confusing array of technical documents which don't really help. The documents seem to say that the Lotus Notes client is not MAPI enabled, but our clients have been told otherwise by Lotus.

The way I understand it, Lotus doesn't use MAPI, but its own API. It is usable, in fact check out idsMail (http://www.intuitive-data.com/idsmail.htm) which uses the same code to use all the Mail Systems. Or at least thats what they claim, and I've heard its very good.