hi,

i want to know whether there exist any limit for no. of users a sendmail
server can support.i want to use sendmail in enterprise with 3500 users.
and please tell me about specific hardware requirements for such type of setup.

also tell me about some good open-source anti-virus s/w which i can use for above setup

thanks,
mand

Amount of users isn't a good gauge, you have to look at the average number of messages. One user could send/recieve 10 messages per day while another guy does 1000.

Your biggest problem will most likely be hardware resources because antivirus and antispam both take a decent amount of CPU time and memory and even with enough resources can add significant latency to mail delivery.

I have SpamAssassin running on a 500Mhz Alpha and it takes ~6s average to scan a message, on a new machine it'll probably be down to a second or lower, but if you've got 3000 messages coming in you won't be able to process them all concurrently so the delay will add up.

I haven't looked at antivirus personally, but I would assume that it will add a similar amount of latency.

Your best bet is to use multiple machine and spread the load across them. Technically you should be using at least 2 machines anyway so that if one dies your email doesn't just stop.

Sorry I can't say anything specifically about sendmail, I use postfix at home and our sendmail boxes at work just hand off mail to our Exchange boxes without much processing.

You might also consider using qmail instead. Not only does qmail have a better security record, it's also used in many large sites such as Yahoo Mail.

I would avoid qmail simply because the author is an asshole and hasn't updated the software in years. Postfix is just as good and is actively maintained.