[CentOS] clustered mail server?

Mon May 19 09:17:56 UTC 2008
Christopher Chan <christopher at ias.com.hk>

John R Pierce wrote:
> Christopher Chan wrote:
>> That default setting is no longer applicable today. Users will scream 
>> if they find out that their mails have been sitting in the queue for a 
>> day. For today's businesses, one day can make or break a deal and so 
>> email, being a much faster form of communication than snail mail, has 
>> come to be seen as the preferred choice. People start calling when 
>> they know they are supposed to get an email in a minute or so when it 
>> does materialize.
> So you never send any email to anyone using greylisting?   thats odd, as 
> its very common nowdays.    greylisting servers will auto-reject the 
> first attempt at sending an email, then accept it on a later retry 
> (typically 10 or 15 minutes is the default retry interval for most mail 
> servers).   This /guarantees/ email will sit in your outbound queue for 
> at least one retry interval.

Yes, so I get to tell the users, sorry, Yahoo is up to its antics again. 
Maybe it will go through in an hour. What advantage would I have in 
putting the queue on a distributed filesystem if I have to ensure that 
the MTAs do not try to both access the queue if they are not sendmail 
versus the simplicity of a local mirrored disk setup for the queue?
> I frequently run into outbound mail that sits in my queues for several 
> hours, the destination servers may be too busy, or they may be offline 
> for maintenance, many reasons.  There's a k12 school district up in 
> Chico CA who's mail server seems to be down as often as its up, and 
> there are several folks on that server who subscribe to various email 
> lists I host.    the mail gets through eventually.

Do you put your outbound mail queue on a distributed filesystem?
> Email is /NOT/ IM.  If your users expect it to function like Instant 
> Messaging, maybe you should suggest they use IM when they want immediate 
> response with feedback.

I am not going to make an issue of their expectations and make them use 
something that is not necessarily available or allowed.
Email + attachments is not quite the same as IM + File Transfers