Sendmail is slow to send mail

October 7, 2013 57.6k views
jurgen271967
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jurgen271967
I noticed that our Rails app gets error when attempting to create a user and it narrowed down to sending a registration email. When I tried to manually test it it turned out that mail actually goes out but with huge delay. It takes 1 minute to process. time echo test | sendmail jurgen@example.org real 1m0.170s user 0m0.008s sys 0m0.004s
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7 Answers
oliversimon October 8, 2013
Hi Jurgen,

If you check your /var/log/mail.log you will probably find something like this: My unqualified host name (localhost) unknown; sleeping for retry. This is because sendmail requires "hostname" to be a fully qualified domain name.

update your "/etc/hosts" file: nano /etc/hosts
to look like this: 127.0.0.1 localhost.localdomain localhost yourhostname

boom, fast sendmail.
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theguycalledsam October 8, 2013
Have you restarted the process?
sudo service sendmail restart
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gtaylor November 26, 2013
If my droplet is for hosting several web sites via virtualhosts instead of a single domain, does it matter what I use for the fully-qualified domain name in /etc/hosts for the purposes of using sendmail?
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kamaln7 MOD November 27, 2013
@Gary: No, as long as it's a FQDN and matches your IP address's PTR record, you're fine.
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ashmenon November 28, 2014

@oliversimon I'm a little new to server management, so pardon me if the questions sound a little stupid, but here goes:

1) When you wrote "localhost.localdomain" and "localhost", those were as is, and not meant to be replaced with anything, correct?

2) my mail.log output showed the following:
"unable to qualify my domain name (pokemon-nyc1) -- using short name"
Does the solution you provided still apply?

3) In the hosts file, I have an existing entry for:
127.0.1.1 pokemon-nyc1 pokemon-nyc1

Am I correct in assuming that the "yourhostname" is, in this case, 'pokemon-nyc1' ? Should the new 127.0.0.1 line then replace the 127.0.1.1 line already existing in the system?

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TheAdministrator May 23, 2016

Try disable IPv6 for whom the first solution didn't work

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simonberton September 7, 2017

You are my hero !!! changing the hosts did the magic !!!

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