Every time a reply is entered in one of the tickets, an email notification is sent to the person/group that this ticket is assigned to (unless configured otherwise).
These emails are really useful for working on issues outside the CRM, like FWDing the mail to a person that is not a part of the CRM. the email has all the customer's information, and also the reply itself, which is perfect.
The thing is, sometimes you miss email because it was deleted, or more likely, when the reply was actually sent, the ticket was not assigned to your or to your group, so you didn't receive this email.
My suggestion is being able to re-send an email notification that was already sent, through the ticket page itself.
Because the ticket does not display a threaded view (meaning there are only options/buttons at the bottom and not for every reply) this will probably only be possible for the last reply - but this could also be a nice advantage.
Maybe in the future this is something that could be considered.