mail / processes

[Nobody's Hero]

We treat sendmail as an application. I support the OS and hardware. My firewall guy says he get tons of these messages:
- refusing a connect on port 25, as no service is listening to the port, message is "stat=Deferred: Connection refused

probably because the max number of sendmail daemons we spawn is 200 and it might not be enough because the port 25 is so busy and we exceed out connection count.

What do you all do out there in the email/sendmail world? Do your servers run more that 200 sendmail processes at a given time?

The reson they set the max at 200 sendmail daemons is to prevent an email bomb or something destructive?

What is your opinion?

[Sandman!]

It might help to know what the -q parameter was set to during sendmail startup? See the sendmail(1M) manpage for details and configure it as follows:

# /sbin/init.d/sendmail stop
# /usr/sbin/sendmail -bd -q1m
# /sbin/init.d/sendmail start

[VK2COT]

Hello,

What is your load average. AT certain oad average, the server refuses SMTP connections.

Check the folling lines in
/etc/mail/sendmail.cf:

# Queue-Only Load Average (option QueueLA): #
# the line beginning O QueueLA=. #
#O QueueLA=8

I saved some customers with similar
problems.

Cheers

VK2COT

[Nobody's Hero]

Here is the qtime setting on the daemon and the load param in sendmail.cf.

ps -ef | grep sendmail 0:00 /usr/lib/sendmail -bd -q15m (sufficient??)

I am also seeing this set in the sendmail.cf file:
# load average at which we just queue messages
O QueueLA=40

# load average at which we refuse connections
O RefuseLA=60

[VK2COT]

Hello,

OK, you accept emails even when the load is quite high :)

What is the result of the following commands:

mailq
mailstats
w
uptime

Cheers,

VK2COT

[Sandman!]

>ps -ef | grep sendmail 0:00 /usr/lib/sendmail -bd -q15m (sufficient??)

Imho reason I suggested lowering the sendmail invocation frequency to 1 min is because it would help clearing the queued messages faster than the default of 30 mins thereby alleviating your denial of service issue.