Rupert Gallagher writes:

By default, Apple Mail downloads all e-mails from? server's account. Previous versions of this client allowed to opt-out. The latest two versions? however, only allow to opt-out from downloading the attachments.

The stress on the server is unbearable. We cannot ask users to be considerate: this is the default behaviour of Apple Mail.

(I'm coming into this thread late.)

I'm having a hard time visualizing the cause of your problem. Most big messages have the bulk of their data as attachments (which you state the mail reader can defer downloading). Also, readers usually cache local copies, so they're downloaded once.

So what the composition of all this traffic? Are you saying the mail client is ultra dumb and repeatedly downloading entire messages, read and unread, attachment and all (i.e. you're truly bandwidth limited?) Do your users typically have many concurrent readers for the same mailbox? What kind of session numbers are you supporting? 100s? 1000s? 10K+?

Your data outflow has an incoming counterpart: if you're having a hard time serving it out, is your MTA also having a hard time with the incoming volume? Can it simply be the case you've underscaled your remote mail service?

Joseph Tam <jtam.home@gmail.com>