Number of connections per IP / POP3

[kilburn]

Quote:well I would never choose a provider with quota below 1gig per mb...

Amazing. I'm having a hard time trying to offer such high quotas for mailboxes, mainly because:

(1) Your mileage may vary, but my customers tend to retain each and every mail they've ever received, including multi-megabyte stupid powerpoint/video jokes and the like.
(2) Backing up *and* being able to quickly emergency-recover multiple (100+) gigabytes of data is not an easy thing to do given my server's limitations (100Mb/s connections). Backup problem: as the maildirs grow, the backup process changed files scan increases quickly (additional stats for each mail). SATA disks really hate processing millions of stat ops for individual files, so the thing turns into a slow beast unless I/O throttled which solves the issue but makes backups slower. Recovery problem: a simple calculation shows it: 100Mb/s ~ 44GB/hour (assuming an ideal network entirely dedicated to the restore process).

How do you handle these situations? Any ideas about them without throwing more/different hardware at it?

Additionally, IMAP clients usually keep open processes in the server. Obviously, people just leaves their mail clients open the whole day while they are working. This means that the number of open imap processes can easily grow to the hundreds, even thousands in busy hours. Do you want this happening to your servers?

Now you might tell me that I'm overloading my servers, but I have to strongly disagree. IMHO, the hardware requirements should grow mainly according to the numbers/bytes of mails received/sent, not to the number of mail accounts.