[CentOS] clustered mail server?

[John R Pierce]

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 That default setting is no longer applicable today.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.

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.

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.