Upping to Major, as this prevents an important part of continuous integration workflow, namely directly identifying and emailing developers the results of their checkins.

In general, mapping from user names to email addresses is the job of plugins implementing MailAddressResolver in Jenkins. It should be pretty automatic if your SCM user names are the same as your Jenkins user names and you're using e.g. LDAP, otherwise, a different implementation may be needed. Still, not really necessary to change the user names returned by P4.

https://wiki.jenkins-ci.org/display/JENKINS/Additional+Identities+Plugin may work for you. It associates additional identities (e.g. p4 user names) to Jenkins user records, and through those, to their email addresses.

I am in an environment where I do require the email address to come directly from the Perforce account info, it's the only available data source.

The email address cannot be inferred from the Perforce username, Perforce users do not necessarily have accounts on the Jenkins server (nor do I want them to if at all possible), nor are all users in LDAP (or any other accessible directory) - using Additional Identities as a workaround would be a real pain.

The email address is easily accessible from the 'user' spec in Perforce. I just need to know how to make it available to the email-ext plugin.

Create an Extension implementing MailAddressResolver from the mailer plugin. This can be an optional dependency to the mailer plugin, with your implementation annotated Extension(optional=true). If the mailer plugin exists and is enabled, p4 will provide the feature, otherwise it won't.

I'm also in the same boat as A C and kind of a deal breaker for the plugin at the moment (don't get me wrong, the plugin is coming along real well). Collecting the email addresses from Perforce appears to be a feature of the other Perforce plugin in case that helps.

I'm curious if I can set hudson.tasks.Mailer.UserProperty.UserProperty. MailAddressResolver claims to look for the email as a UserProperty:

So the common technique for a mail address resolution is to define your own {@link UserProperty} types and
add it to {@link User} objects where more context is available. For example, an {@link SCM} implementation
can have a lot more information about a particular user during a check out, so that would be a good place
to capture information as {@link UserProperty}, which then later used by a {@link MailAddressResolver}.

Code changed in jenkins
User: Paul Allen
Path:
src/main/java/org/jenkinsci/plugins/p4/changes/P4ChangeEntry.java
src/main/java/org/jenkinsci/plugins/p4/client/ConnectionHelper.java
http://jenkins-ci.org/commit/p4-plugin/5f936ad0fffc3212a1960b1d7c67c3807c657fe4
Log:
Add Perforce User's email to Jenkins User property.

JENKINS-28421

Code changed in jenkins
User: Paul Allen
Path:
src/main/java/org/jenkinsci/plugins/p4/changes/P4ChangeEntry.java
http://jenkins-ci.org/commit/p4-plugin/e117cd2c9d1a33745191f5c326d4efb0184ace85
Log:
Only set email if User's address in null or empty.

JENKINS-28421

Code changed in jenkins
User: Paul Allen
Path:
src/main/java/org/jenkinsci/plugins/p4/changes/P4ChangeEntry.java
src/main/java/org/jenkinsci/plugins/p4/email/P4AddressResolver.java
src/main/java/org/jenkinsci/plugins/p4/email/P4UserProperty.java
src/main/resources/org/jenkinsci/plugins/p4/email/P4UserProperty/config.jelly
http://jenkins-ci.org/commit/p4-plugin/c1f15ea19c720a3d4840aafa478b177c0d0f8f97
Log:
Created P4UserProperty to store Email address.

P4UserProperty extends UserProperty to store the Perforce User’s email.
Then retrieves it with P4AddressResolver by extending
MailAddressResolver.

JENKINS-28421

Fixed 1.3.0