Web Hosting Talk : Web Hosting Main Forums : Hosting Security and Technology : Qmail smtp slow

[jezza]

Hi,

Apologies if this has been covered before, but my qmail smtp server is acting very slow. If I telnet to port 25 on localhost it's quick, but if I do the same from a remote machine It takes ages to respond. I'm guessing it's a DNS problem, but the server's name resolves OK, as does the machine I'm coming in from. Does anybody have any ideas? Your help would be very much appreciated.

Thanks
Jez

[stftk]

If you want to post or PM the domain I can run some DNS checks on it.

[pmabraham]

Greetings:

Run a http://www.dnsreport.com/ on the domain name.

The main A record and www record (a or cname) may be ok; the mx may have problems.

Other things to check:

/etc/resolv.conf on the mail server -- are the entries correct?

Are you using the paranoid switch for tcpservers for the qmail start up? That can delay the connection to port 25 from the outside.

Thank you.

[jezza]

Thanks all,

I checked with dnsreport.com, and found some problems with my nameservers, but I still have the slow smtp problem.
I'm using xinetd to start qmail.

Jezza

[jezza]

Ah,

It turns out that my ISP Freeserve (now wanadoo) forces all port 25 traffic via their own web servers!

Thanks for your help guys.

Jez

[davila]

try to disable reverse lookups by editing /etc/xinetd.d/smtp and add -Rt0 after server_Args like this :

server_args = -Rt0

[blockcipher]

I have checked all of the above and still have this problem. POP3 is quick, but sending out mail takes forever. Any ideas?

[dan_erat]

Make sure that you're not checking any broken DNSbls from rblsmtpd, if you're using it.

[blockcipher]

I don't think I'm using anything like that. Its a Plesk 7.0.3 system and I think it came with the basics. Is there a file I need to look at that will tell me this?

Sorry for the dumb questions I have no experience with qmail

[BigGorilla]

Couple suggestions (some already mentioned)....

1) Make sure the machine is resolving hosts properly. Consider using a caching DNS server locally on the machine to speed up queries (such as djbdns). Make sure to put 127.0.0.1 as the first line of your /etc/resolv.conf if you install a local caching DNS.

2) Check your rbl setups as mentioned.

3) How big is your mail queue (run qmail-qstat as root from a shell prompt)? Qmail can run slower if the mail queue is large (but usually not unless the queue size is 10's of thousands or 100's of thousands in size).

Also, it's generally recommended qmail runs behind ucspi-tcp and not xinetd for better performance, but I am not familiar with Plesk's setup.

[blockcipher]

The queue size is extremely small as of now. This dedicated box only has one site on it. Not alot of mails go through it. As for my resolv.conf file. Everytime I edit it, it changed. Probably plesk doing that.

[dan_erat]

Please paste the output of "cat /etc/xinetd.d/smtp" (if that's where qmail-smtpd is being started).

[blockcipher]

[root@u15149596 etc]# cat /etc/xinetd.d/smtp
cat: /etc/xinetd.d/smtp: No such file or directory
[root@u15149596 etc]#

I also found this, this the one you talking about?

[root@u15149596 xinetd.d]# cat /etc/xinetd.d/smtp_psa

service smtp
{
socket_type = stream
protocol = tcp
wait = no
disable = no
user = root
instances = UNLIMITED
server = /var/qmail/bin/tcp-env
server_args = /var/qmail/bin/relaylock /var/qmail/bin/qmail-smtpd /var/qmail/bin/smtp_auth /var/qmail/bin/true /var/qmail/bin/cmd5checkpw /var/qmail/bin/true
}
[root@u15149596 xinetd.d]#

[blockcipher]

When changing it to:

server_args = -Rt0 and then service xinetd restart

Mail won't even send. So that doesn't seem to work on my box.

Just an update

[blockcipher]

Oh goodness. This was my fault I put that in the lines on its own, sorry! I put -Rt0 before the other commands and that seems to work. Sorry to have put you out of your way guys. I really do appreciate the help. I'm all fixed up!