It would help out a lot if we could manually re-trigger/send again emails to specific recipients.
Whenever a Learner or otherwise doesn't receive an expected email, we check for a copy in the BCC mailbox, and if it doesn't exist there either, we have to utilize the send update email. This requires a series of small edits and saves in between to minimize sending updates erroneously and confusing recipients.
As a recent example, instructors for an ILC never received the instructor notification email. We didn't have a copy in the BCC either, suggesting the messages never delivered in the first place. At this point we can turn off the general session update email, save & exit, return, "edit" the session, save again to trigger the Instructor Update email, exit, return once the update email goes out and turn the general update email on again. This is even more cumbersome when the email needs to go to a specific learner.
The whole process would be much easier if we we could re-trigger the initial enrollment email with the option to select intended recipients.
Or perhaps, a general solution could be a button associated with each session to send a "Custom" email. This would need to include the option to select recipients too, and utilize variables and snippet tags for templates, but wouldn't rely on triggers.