Bamboo's email notifications include all authors who committed for that build. For example:

[Bamboo] HedgeHog - Trunk build 19469 has FAILED (5 tests failed, no failures were new). Change made by Tian Li, Andrew Aymeloglu and Jon Kean

Since a failure involving your commit requires immediate attention, many developers have setup email filters to notify them when their name appears in the subject line.

Unfortunately, if lots of people committed at once, Bamboo will not display everyones name, and instead simply say:

[Bamboo] HedgeHog - Nightly build 464 has FAILED (3 tests failed, 2 failures were new). Change made by 8 authors

Which causes the email to be skipped entirely by these dev's email filter, causing the failure to be ignored by nearly everyone.
All user names do appear inside the email body, but it's quite frequent for dev's to add other names to commit comments, making it unreliable to filter on the email body.

Feature request:
Please add an option to always display all user names in the subject line.