Truncation of Majordomo digest messages?

Something very weird has started in the last few weeks, about the same time
I turned on the remote_max_parallel to 10.

Lots of lengthy Majordomo digests are being truncated in the *middle* then
resuming with a large chunk missing! The only finger I can point is at
Exim because the archived digest is intact. Could the remote_max_parallel
be foobar?