Re: [cobalt-users] A Dedicated mail server

[Bruce Timberlake <bruce@xxxxxxxxxx>]

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> I think about to use a dedicated mail server with a Raq4, 30Gb Hdd
> and 512Mb or 1Gb ram

So you have about 300 domains, currently spread across 3 RaQ 4 
servers, and each RaQ is currently handling the email for its own 
domains.  And you want to set up a 4th RaQ as just a mail server for 
all those domains, so that all mail for any domain goes to the 
separate RaQ?

Is there a specific reason you wish to have this setup, instead of 
leaving it as is?  The setup and synchronization between the 2 can be 
tricky; you should have a very good reason for breaking this apart if 
it's currently working sufficiently.

> I think that the main problem we will have, is that we have to
> create the 300 'mail sites' on the mail server... I'm right ?
> And, we will have to create all the www.*domain*.* in the form of
> mail.*domain*.*   Is that also right ?

Yes, you will need separate host names for each 'mail' domain, and 
having them all be 'mail.example.com' is an easy way to do it.

The major problem, though, is that you have to create an account for 
each user on the mail server.  If they are also doing web stuff, 
they'll have an account on the web server as well.  You also need to 
ensure that the 'web' servers don't have any mail server alias 
entries in the Site Settings...

> Then, we will have to modify all our MX records, to point to all
> the mail domains.

Correct.  You'll need an "A" record for mail.example.com, pointing to 
the IP address on the 'new' server.  You will also need two "MX" 
records, for 'example.com' and 'www.example.com', each pointing to 
'mail.example.com'

> Here, i think about to do a 'search and replace' in the
> named/records file, and replace every High www.* to High mail.*  
> and to filter the domains that should not point to the mail
> server... ;) Is that ok ?

Yes, copying the 'records' file to the new server is a quick way to 
move DNS record information. But that implies that the new 'mail' 
server will be providing DNS info for the new 'mail' domains.  
Currently, it sounds like each RaQ is a DNS server for the domains it 
hosts.

> Also, i thinked that we can disable the FTP services, to make that
> our customers can't upload/download something on the mail server.

Yes, disable all services you won't be using.  That's true on _any_ 
server.

> I remember also, that there is a 'soft' limit to 250 or 255 max
> sites, but this can be modified.

Correct, there is a 250 domain limit set in Product.pm

> But, can Apache support all the 300 domains ?

If you'll be using this as a mail server only, Apache doesn't matter. 
But yes, it will handle many more domains... the UI becomes a bit 
unwieldy with lots of domains on the server, but it will work.

> Should we have to use 2 IP's, and share the 300 (and growing)
> domains on the 2 IP's ?  Is this working ?

So you want to put all the mail domains on the separate server and 
split them among 2 IP addresses?  You can leave them all on one IP if 
you want... there's really only one sendmail running, listening on 
one IP address.  You're just telling it that it's ok to accept mail 
for the other 299 domains as well.

You only need unique IP addresses if you need SSL, Anonymous FTP, or 
per-site Bandwidth Management.  Otherwise, one IP is sufficient for 
all other services.

> Is a Raq4 with 30Gb hdd and 512Mb ok ?  (most people use 5 or 10Mb
> for the mails)

Disk space could be an issue if you're running IMAP and allowing users 
to keep mail on the server.  Otherwise, if they are POPping their 
mail off, 30 GB should be ok... depends on your users, though, and 
how much email they receive and how often they check/remove it.

> Or do you recommand to put 1Gb ram ?  (This work fine for us...;)
> Or a bigger HDD ?

Bigger is always better... :)

> And, last question, how many times should our customers let the old
> www. xyz mail domain in the mail software? 24 hours after the DNS
> changes, + 24 hours more, to be sure ?

That depends on how long it takes for the DNS to propogate around the 
internet... I'm sure some of the DNS gurus (Jeff?) can comment much 
more authoritatively on the sequencing of DNS moves from one server 
to another.

Moving the mail receipts from one server to another without 
interrupting mail service to the customers, especially if they have 
to change their mail software, is not a 'simple' task.  Again I 
question why you are considering this for all your domains in the 
first place.

> Should the local scripts (like formmail's) work, also if the mail
> server is not on the local server ?

If the local server does not have any mail server alias entries, the 
'web' server should be able to send mail to the 'mail' server without 
a problem.  If there are mail server alias entries, the 'web' server 
will see that the destination domain is 'local' and not send the mail 
to the 'mail' server...

- -- 
Bruce Timberlake

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