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Cocorico
Asked: 2012-05-18 21:06:56 +0800 CST

Perl script is sending mail very slow via sendmail - one mail every 30 seconds

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I have a perl script that sends mail out to a mailing list.

On my old dedicated server, it worked fine, and sent one email per second basically. I recently switched to a new dedicated server, with about the same specs, and it's going extremely slow, about one mail every 30 seconds. I set up a test script to watch what part takes the longest:

open(MAIL,"| /usr/sbin/sendmail -tv -d8.7 $recipient_email");
print MAIL <<EOF;
From:Test Sender <$sender>
To:$recipient_email
Subject:Testing

Justw ant to see how long this takes

EOF
close(MAIL);

The -d8.7 there is a debug option that lets me watch the output of the script. I will paste that here, there are 3 spots which both hang for too long, I will mark them here:

dns_getcanonname(receiving_server.com, trymx=1)

dns_getcanonname: trying receiving_server.com. (A)

5 second delay here YES

dns_getcanonname: receiving_server.com

getmxrr([127.0.0.1], droplocalhost=1)

andrew@receiving_server.com... Connecting to [127.0.0.1] via relay...

220 my_server.com ESMTP Sendmail 8.13.8/8.13.8; Fri, 18 May 2012 06:55:04 +0200

>>> EHLO localhost.localdomain

250-my_server.com Hello localhost.localdomain [127.0.0.1], pleased to meet you

250-ENHANCEDSTATUSCODES

250-PIPELINING

250-8BITMIME

250-SIZE

250-DSN

250-ETRN

250-DELIVERBY

250 HELP

>>> MAIL From:<[email protected]> SIZE=115

10 second delay here

250 2.1.0 <[email protected]>... Sender ok

>>> RCPT To:<andrew@receiving_server.com>

>>> DATA

5 second delay here

250 2.1.5 <andrew@receiving_server.com>... Recipient ok

354 Enter mail, end with "." on a line by itself

>>> .

250 2.0.0 q4I4t4Lu014501 Message accepted for delivery

andrew@receiving_server.com... Sent (q4I4t4Lu014501 Message accepted for delivery)

Closing connection to [127.0.0.1]

>>> QUIT

221 2.0.0 my_server.com closing connection

As far as I can tell, my /etc/hosts and /etc/resolv.conf seem fine, and these are the only things that Google suggests might be broken, anyone have any ideas?

sendmail

1 Answers

  1. It looks like

    1. Delay to resolve name via DNS
    2. Recipient check by remote SMTP server
    3. Sender check by remote SMTP server

    Is the remote server the same as before? Do you have any visibility of that server?

    Have you run tcpdump on that interface to see if there is any protocol activity during the gaps? Try this (as root) -

    # tcpdump -vvv -w output.pcap -i eth0 'port not 22'

    This will capture all traffic except your SSH session traffic and output to the file 'output.pcap'.

    I don't suppose there's any chance you've moved to an IP that is on a blacklist somewhere? Sites like the following can help you find out -

    http://www.mxtoolbox.com/blacklists.aspx

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