Creating this for an add-on developer:
JIRA Cloud has the right idea; we can say goodbye to blowing up mailboxes with JIRA emails. The problem is that it's currently impossible to only receive messages I care about, making the integration far less useful than it could be.
So what do I want?
I want to receive Slack messages for events which I care about, namely events on issues I'm watching and @mentions in issues I'm not watching. I also want to control whether all of those messages cause Slack notifications, or just @mentions.
Right now, @jirabot can't be configured to only send messages for events I care about. If I connect @jirabot using direct messages, for example, I get a notification for EVERY event in a project. Yes, I can customize @jirabot to only send certain types of issues, but the type of issue has no bearing on whether I'm watching it. That's a non-starter.
Instead of DM, I can create a Slack channel that receives all JIRA messages to avoid the flood of notifications, but that has the opposite problem. Nothing's ever a notification, even if I care about it, so events on the issues I watch never get noticed.
I think the right solution here is to be able to configure JIRA Cloud to send me only messages that affect me from the get-go, instead of making Slack trying to figure out what to notify on and what not to notify on.
Side note. One stop-gap solution I tried which didn't work was to send all JIRA messages to a single Slack channel, and try to get Slack to create notifications whenever my name appears using Slack highlight words. But this didn't work, even for explicit @mentions in JIRA issues. According to an email I got from Slack,
One thing to note: this highlight word limitation [not notifying] is for bot messages which originate from an incoming webhook. Slack does recognize highlight words from a Bot User. I'm not sure if you will be able to take advantage of Bot Users in your specific case, but it might be worth exploring. Here's some documentation about Bot Users (https://api.slack.com/bot-users) and you can add one to your team here: https://my.slack.com/apps/A0F7YS25R-bots.
Even though JIRA Cloud is a bot user, highlight words didn't trigger notifications. At any rate, this would have only been a stop-gap solution, since a highlight word (my name) wouldn't necessarily show up in every message for every issue I'm watching. The right solution is to configure @jirabot.