[Dovecot] dovecot and virtual hosting

[Brian Candler]

On Wed, Jun 02, 2004 at 08:06:14PM +0200, Vegard Svanberg wrote:
> A usual hosting provider setup depends on having one IP ("virtual
> mailserver") per domain.  Using dovecot on servers handling hundreds or
> thousands of domains today equals to having multiple instances of
> dovecot running. 
> 
> This problem could be solved by making dovecot take into account the IP
> address the user connects to and authenticate against the proper
> {database, table, pw-file, [...]} based on that.
> 
> Comments? 

I've worked at very large ISPs, and we never did virtual hosting based on IP
address; we simply made the logins unique.

- some systems used logins like abc123456, where 'abc' is a prefix
  specific to that ISP, and '123456' is a sequence number

- other systems used username at domain as the login (i.e. the primary E-mail
  address of the mailbox)

You would be very hard pressed these days to justify to RIPE/ARIN/APNIC that
you want hundreds of IP addresses just for virtualising POP3 mailboxes
(similarly FTP servers for uploading website contents).

Even migrating existing ISPs was not a problem; the logins never clashed.
Perhaps we we fortunate that in the odd occasion where two different
systems had been using the same prefix 'abc' for logins, that they used
different ranges of sequence numbers.

Regards,

Brian.