Will speed of the new system be good enough, even if a user with the 2GB mailboxes starte to delete spam mails.
CPU speed is rarely the issue. IMAP servers tend to be I/O bound.
Will the IO load of the system be large.
Yes. The more spindles you have (as opposed to single gigantic disks), the better. Definitely separate the mail spool on a different disk from user mailboxes.
how does Imap 2002d delete a message from a mailbox, will it do a copy of the entire mailbox or can it delete a message in one large file without to much IO.
It depends upon the mailbox format. In traditional UNIX format, it has to rewrite the mailbox from the point that the deleted message is located to the end of the mailbox.
-- Mark --
http://staff.washington.edu/mrc Science does not emerge from voting, party politics, or public debate. Si vis pacem, para bellum.
