it would be great if we could configure Jira to query Active Directory for distribution group membership when a email list is added to a Jira issue.

e.g. we often have the need to add an email mailing list address as a watcher to a Jira issue so that a logical group of staff are all kept up to date on an issue. the problem arises when an individual who is also a member of said mail list is listed individually as the reporter, the owner, or a watcher of an issue; in this case that person can receive multiple copies of the message. if Jira were to query AD to see that the reporter (e.g. user "x" with email addr "x@abc.com") is also a member of the email list (e.g. "abc@abc.com") which is specified as a watcher, then Jira could determine that it does not need to send mail to "x@abc.com" as the mail sent to "abc@abc.com" will already hit "x@abc.com".

of course this gets very complicated when multiple mail lists are involved or when lists have sub-lists.

as an alternative, if Jira sent email to all addresses as one message, rather than one message per address, then most MTAs and/or MUAs are smart enough to weed out duplicates.