Sendmail在Centos VPS上非常慢

Question

My vps has recently started having issues with sendmail being very slow. This is the same for email sent using PHP with the mail function or from the command line using the mail command. I know this probably isn't enough information but here is the logs to start:

#Appears about 8 seconds after the mail command is run
Mar 29 11:09:12 vps-1006136-254 sendmail[23362]: r2TF9732023362: from=apache, size=203, class=0, nrcpts=1, msgid=<201303291509.r2TF9732023362@vps-1006136-254.manage.myhosting.co
m>, relay=apache@localhost

#PHP mail command was run at 11:09:19
Mar 29 11:09:27 vps-1006136-254 sendmail[23366]: r2TF9CIU023366: from=<apache@vps-1006136-254.manage.myhosting.com>, size=470, class=0, nrcpts=1, msgid=<201303291509.r2TF9732023
362@vps-1006136-254.manage.myhosting.com>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
Mar 29 11:09:27 vps-1006136-254 sendmail[23362]: r2TF9732023362: to=jeremy.m.fry@gmail.com, ctladdr=apache (48/48), delay=00:00:20, xdelay=00:00:15, mailer=relay, pri=30203, rel
ay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (r2TF9CIU023366 Message accepted for delivery)

#email finally sends 
Mar 29 11:09:57 vps-1006136-254 sendmail[23376]: STARTTLS=client, relay=smtp.vps.myhosting.com., field=cn_subject, status=failed to extract CN
Mar 29 11:09:57 vps-1006136-254 sendmail[23376]: STARTTLS=client, relay=smtp.vps.myhosting.com., field=cn_issuer, status=failed to extract CN
Mar 29 11:09:57 vps-1006136-254 sendmail[23376]: STARTTLS=client, relay=smtp.vps.myhosting.com., version=TLSv1/SSLv3, verify=FAIL, cipher=DHE-RSA-AES256-SHA, bits=256/256
Mar 29 11:09:58 vps-1006136-254 sendmail[23376]: r2TF9CIU023366: to=<jeremy.m.fry@gmail.com>, ctladdr=<apache@vps-1006136-254.manage.myhosting.com> (48/48), delay=00:00:31, xdel
ay=00:00:31, mailer=relay, pri=120470, relay=smtp.vps.myhosting.com. [168.144.1.236], dsn=2.0.0, stat=Sent (OK id=1ULawH-0002KK-BM)

My issue is that it seems that PHP's mail function seems to wait the full 30+ seconds before returning true and it causes some of my contact forms to seem unresponsive. Does anyone know what I can do to speed this up, or where to look next for more info?

Answer 1

Okay I submitted a ticket to my VPS host and they "could not replicate" the issue. However I do have a new nameserver in my /etc/resolve.conf file pointing to Google DNS server (8.8.8.8).

Looks like it was a DNS resolution issue, the new nameserver has fixed the problem. Also yum is much faster now since it can find mirrors without delay too.