[Dovecot] order of variable modifiers

[Phil Howard]

I'd like to have a variable substitute take the domain name part, lower case
it, MD5 it, and take a 2-character substring of that.  Would that be like
%2MLd ?  The documentation on the H hash modifier described reversing with
R, but expresses it at %3RHu which seems to me like it would be reversing
the hash result rather than the user string.

I'm undecided about MD5 vs. hash, and could go either way.  But I was
thinking:

mail_location = /data/mail/%2MLd/%Ld/%2MLn/%Ln