nnimap-split-rule regex: match newlines

[Kurt B. Kaiser]

I'm trying to split on two headers which are separated by a couple of
lines.  But I haven't been able to figure out how to match the newlines.
I have:

        ("INBOX.SomeMailbox"
         "^From:.*avendor\\(.*[ \t\n]\\)*Subject:.*Order Confirmation")

I started with 

"^From:.*avendor.*Subject:.*Order Confirmation" but '.' doesn't match
a newline.  I tried progressively more complicated regex but no joy.

-- 
Thanks, KBK