Having never done this myself Im not sure. If you look at the config files just after creation are the settings there?

Hello David,

the weird thing is, that this issue is only present after you try to send the first email notification. This action somehow clears the email configuration entry.
If you configure it then using the web front-end and store the config again, it works fine without further issues.

Configuration after Jenkins started

{{<?xml version='1.0' encoding='UTF-8'?>
<hudson.plugins.emailext.ExtendedEmailPublisherDescriptor plugin="email-ext@2.61">
<defaultSuffix>@suffix.com</defaultSuffix>
<smtpHost>smtp2.local</smtpHost>
<useSsl>false</useSsl>
<defaultSubject>$PROJECT_NAME - Build # $BUILD_NUMBER - $BUILD_STATUS!</defaultSubject>
<defaultBody>$PROJECT_NAME - Build # $BUILD_NUMBER - $BUILD_STATUS:

Check console output at $BUILD_URL to view the results.</defaultBody>
<defaultPresendScript></defaultPresendScript>
<defaultPostsendScript></defaultPostsendScript>
<defaultClasspath/>
<defaultTriggerIds/>
<emergencyReroute></emergencyReroute>
<maxAttachmentSize>-1</maxAttachmentSize>
<recipientList></recipientList>
<defaultReplyTo></defaultReplyTo>
<excludedCommitters></excludedCommitters>
<overrideGlobalSettings>false</overrideGlobalSettings>
<precedenceBulk>false</precedenceBulk>
<debugMode>false</debugMode>
<requireAdminForTemplateTesting>false</requireAdminForTemplateTesting>
<enableWatching>false</enableWatching>
<enableAllowUnregistered>false</enableAllowUnregistered>
</hudson.plugins.emailext.ExtendedEmailPublisherDescriptor>}}

Configuration after the first notification

{{<?xml version='1.0' encoding='UTF-8'?>
<hudson.plugins.emailext.ExtendedEmailPublisherDescriptor plugin="email-ext@2.61">
<useSsl>false</useSsl>
<charset>UTF-8</charset>
<defaultSubject>$PROJECT_NAME - Build # $BUILD_NUMBER - $BUILD_STATUS!</defaultSubject>
<defaultBody>$PROJECT_NAME - Build # $BUILD_NUMBER - $BUILD_STATUS:

Check console output at $BUILD_URL to view the results.</defaultBody>
<defaultPresendScript></defaultPresendScript>
<defaultPostsendScript></defaultPostsendScript>
<defaultClasspath/>
<defaultTriggerIds>
<string>hudson.plugins.emailext.plugins.trigger.FailureTrigger</string>
</defaultTriggerIds>
<emergencyReroute></emergencyReroute>
<maxAttachmentSize>-1</maxAttachmentSize>
<recipientList></recipientList>
<excludedCommitters></excludedCommitters>
<overrideGlobalSettings>true</overrideGlobalSettings>
<precedenceBulk>false</precedenceBulk>
<debugMode>false</debugMode>
<requireAdminForTemplateTesting>false</requireAdminForTemplateTesting>
<enableWatching>false</enableWatching>
<enableAllowUnregistered>false</enableAllowUnregistered>
</hudson.plugins.emailext.ExtendedEmailPublisherDescriptor>}}

Very weird, if you restart the container after initial creation do the settings stay then?

Yes, I don't think the issue is related to Docker itself. The first attempt to send an email after the very first Jenkins start leads to the behaviour described above.

In the first set of XML (before the first notification is sent), overrideGlobalSettings is false, this means that email-ext will try and upgrade from the settings for the mailer plugin, which if they are empty will overwrite your settings with empty settings. You need to see if you can set the overrideGlobalSettings, or set the same settings for the mailer plugin during container setup so this does not occur.

slide_o_mix Thank you! Seem to resolve the problem.