Jenkins ver. 1.598
Debian Wheezy 32bit

Need a bit more information on this. How do you have your job configured? Which email plugin are you using (Mailer or email-ext)?

I'm sorry, I thought I did describe it better.

The mail server is configured as 'mygit' with 'mygit' in /etc/hosts as '1.2.3.4 mygit'.

The job is configured to send an email notification to 'proj_myapp' for every unstable build.
'proj_myapp' is an alias that is configured on 'mygit', and to which I can send email without problems.

Before this used to work just fine.
I don't know which version of Jenkins broke it since I don't regularly update Jenkins and don't have failing builds very often.

It still doesn't work for Jenkins 1.607.

Which mailer plugin are you using? Also, which version of Jenkins did it work on?

mailer = the default Jenkins mailer, currently @ 1.15

which version: (as I said) I don't know. probably a few versions before I filed the bug

Can you provide a config.xml for the job and a build log?

The xml I can only provide privately.
The part relevant to email:

    <hudson.tasks.Mailer plugin="mailer@1.12">
      <recipients>proj_nbsolsrd</recipients>
      <dontNotifyEveryUnstableBuild>false</dontNotifyEveryUnstableBuild>
      <sendToIndividuals>false</sendToIndividuals>
    </hudson.tasks.Mailer>

There is nothing special in the build logs.

Failed build:

Build step 'Execute shell' marked build as failure
Archiving artifacts
An attempt to send an e-mail to empty list of recipients, ignored.
Started calculate disk usage of build
Finished Calculation of disk usage of build in 0 seconds
Started calculate disk usage of workspace
Finished Calculation of disk usage of workspace in 0 seconds
Finished: FAILURE

Next successful build:

Archiving artifacts
An attempt to send an e-mail to empty list of recipients, ignored.
Started calculate disk usage of build
Finished Calculation of disk usage of build in 0 seconds
Started calculate disk usage of workspace
Finished Calculation of disk usage of workspace in 0 seconds
Finished: SUCCESS

My guess is that Mailer tries to resolve proj_nbsolsrd to a username, which is can't do and so it replaces it with an empty string. Can you try setting up a user in the Jenkins database with the username proj_nbsolsrd and specify the email address as proj_ngsolsrd and see if that works?

I really don't want to do that for real.
I can try it for a test but not as a solution.
Tomorrow I can try.

Mailer shouldn't ever try to resolve the name, the MTA will return an error when the name is not valid, it's not Jenkins' business to try to do the MTA's work.

As I said, proj_xxx is a valid alias on the MTA, the MTA can resolve it just fine.

then it should just assume entries that it can't resolve to be valid. removing such entries really is a mistake

Its just a theory, i don't know for sure. I don't maintain mailer, just trying to help out.

Looks like it will not send if it can't resolve. https://github.com/jenkinsci/mailer-plugin/blob/5049c6360ac14597a7336b88274adb867f255e84/src/main/java/hudson/tasks/MailSender.java#L444

Guys,

Please please fix this!
I marked it critical for a reason.

There really is no need to remove 'unresolved' entries: if mail can't be sent the the mail server administrator will get reports from the mail agent.

This is truly killing our workflow.

I don't know if there is currently a maintainer for the Mailer plugin.

Well, someone can easily fix this, right?
The offending commit was already identified.

Which commit was identified?

See https://github.com/jenkinsci/mailer-plugin/pull/20

Please release the plugin right after pulling this in