When email-ext has to send two emails, from two different jobs failing at the same time, the same body appears in the two emails.
The subjects are correct.

This morning, two unrelated jobs started and failed at exactly the same moment: the build date/time is the same, down to the second. They both lasted a quarter of a second. Both triggered a 'Failure' mail. The two subjects in the mails were different, as expected. But the mails had the same body. The body was correct for one job (i.e. it's not two bodies mixed, it's two copies of the same body that is fine for one of the jobs).

A lock missing when generating the mails?