[Dovecot] rule of thumb for indexing overhead

[WJCarpenter]

> We use exim all the way to local delivery. And it handles Maildir++
> quotas just fine.

Ah, right.  I was misremembering.  It's the DB-stored quotas in dovecot that I was thinking of using some time back.  Sorry for
my misstatement.

> of indexing during delivery are negligible for us in general and
> potentially negative in some scenarios (mass mail to many/all users).

Is this negative hypothetical or have you actually seen load spikes in situations like this?

> I don't think there are many situations where a MTA can do better
> than a LDA when it comes to rejections during SMTP time. Since at

I agree.  The opportunities are more theoretical than practical.  If you include processing user .forward files as part of the
exim recipient verification or if you include a quota check after SMTP DATA ....