[ale] Sendmail latency

[Ryan Fish]

> --- Ryan Fish <FishR at bellsouth.net> wrote:
>
> > > You are correct that sendmail (mail in general too) is heavily
dependent
> > > upon dns.  Ping alone doesn't necessarily test dns.  Can you 'host'
each
> > > machine name and ip successfully?
> >
> > - When I 'host' the app server from the mail server I only receive
> > 192.168.3.0
>
> Hmmm, that should be a valid IP address (although .0 is probably usable),
> something like 192.168.3.1.

- The actual IP for this app server is .221 so I have no idea why it is
coming back as .0

>
> > - When I 'host' the mail server from the app server I receive the full,
> > proper IP address
> >
> > > Make sure that the order is files,dns when you
> > > "grep hosts /etc/resolv.conf"
> >
> > - This results in no output on either server.  I know what you are
looking
> > for though but cannot remember the file to look in at this time...
>
> Sorry, I meant /etc/nsswitch.conf

[root at mailserver mail]# grep hosts /etc/nsswitch.conf
#hosts:     db files nisplus nis dns
hosts:      files dns

[root at appserver etc]# grep hosts /etc/nsswitch.conf
#hosts:     db files nisplus nis dns
hosts:      files dns


>
> > > How many emails does the java applet send at once?  Are we talking
> > > hundreds or thousands?
> >
> > - Thousands.  When I spoke with the client around 8:30P EST tonight
there
> > were 7500 msgs in the queue used by the Java app on the App server.
> > Typically that queue is cleared almost instantly.
>
> It could be that the sendmail queue is getting backlogged due to latency
at
> other (receiving) mail servers.  List would be indicated in the "stat"
output
> of each connection attempt in /var/log/maillog.   Check also for any
errors in
> /var/log/maillog indicating connection limiting due to high load average?

Everything worked fine prior to rebooting the app servers around 5A on
14JAN.  Afterwards all of this started...

I see very few errors in the maillog.  Here is a sample of some:

Jan 24 23:24:33 mailserver sendmail[5617]: j0LHsHCx010652:
to=<user at outsidedomain.com>, delay=3+10:30:11, xdelay=00:00:00,
mailer=esmtp, pri=7327408, relay=mail.outsidedomain.com. [38.113.1.50],
dsn=4.3.0, stat=Deferred: 451-host lookup did not complete

Jan 24 23:27:56 mcmail02 sendmail[5617]: j0LFWuTF026717:
to=<user at otherdomain.com>, delay=3+12:54:55, xdelay=00:00:15, mailer=esmtp,
pri=7502182, relay=otherdomain.com. [38.161.171.51], dsn=4.0.0,
stat=Deferred: Connection refused by otherdomain.com



- I don't know how to obtain the 'stat' output of connections in
/var/log/maillog...

-Ryan