I've been trying out Snappermail Enterprise v 2.x, and it works very well in
general.

But: Many, though not all, of the messages sent to me from my company's
Lotus Notes emailer have normal headers but empty content. I can see sender, subject and date but nothing in the message body. I can't
understand why.

I'm retrieving the messages by IMAP, SSL, from a Fastmail account.

Any suggestions?