I've noticed that the email-ext plugin will not send out notifications to emails beginning with a '#', even though the job console states that it is doing so. For example:
Build step 'Execute shell' marked build as failure
Discard old builds...
Email was triggered for: Failure - Any
Sending email for trigger: Failure - Any
Sending email to: #firstname.lastname@example.org
The email-ext plugin is fine if the email does not begin with a '#'.