Not sure I fully follow what you need here, but I can address some of it. For inbound email channel to a JSM space, there is the built in email channel. However, I believe there is only one email address allowed per JSM space. (I could be wrong about this). There are limitations. There is a size limit of 25MB total per email. Anything above that either won't be ingested or only partially, which means attachments in the email may not make it into the work item, if that's necessary to your workflow. To get around this limit for a project, I actually used Claude Code to write a Forge app for email ingestion. It listens to a shared email box and ingests everything into the JSM WRKHUB space. Automation rules inside WRKHUB then check for codes in the email / summary field to determine what kind of request it is (work type) and then routes a clone of the work item to an appropriate JWM space for the specific team to do the work requested. WRKHUB is just a passthrough for ingestion then team assignment. Mail flow rules in my M365 tenant can route emails from many different shared email boxes all into the one email box that my Forge app listens to, adding codes to the subject lines so WRKHUB knows where they originated. It works, it's fairly simple, yet gives us unlimited email flows into it.

For outbound emails, especially from a distribution list of any size, you're going to hit a real limit on the number of emails you can send out in one batch or in one day from a single email box. When you send email out via an action in an automation rule, it will come from automation@[companyname].atlassian.net by default, although you can tweak that in the action step setup. But I think there will still be some type of limit on volume from Atlassian. The real issue with volume emails being sent is you don't want your company to become known as a spammer in the greater interwebbed world. I've worked with a third-party Marketplace app called Email This Issue which has inbound and outbound email handling capabilities. It's pretty robust, but a bit challenging to set up. It does work though, and it MIGHT have broader volume limits. The only other real solution would be to create a way to connect to a mailing company like MailChimp or MailerLite or something similar to avoid the email limitations. We do something with Mailchimp ourselves, but I'm not part of that team so I'm not familiar with how that was setup (and it is wired into our custom web app, not Atlassian, but the concept would be the same I think).

Thanks, Josh. I appreciate the feedback. It dovetails with what I suspected is the case. Kind of the Atlassian way, I guess. As I did more research, I'm seeing some not so great feedback on CSM anyway, and the last thing I want to do is rely on yet another half-baked app that does a fraction of what it is supposed to do. Have a good one!

@Alex Ortiz @Chris Rogers Really appreciate the insight. Atlassian market a super idea and deliver a half-backed solution? Color me shocked (not). ATL products definitely have an interesting lifecycle. We can almost watch them grow up from infant to toddler to juvenile to adult. What we get eventually is a much different "animal" than what we start with - or rather what the marketing team told us we would get. Makes me think of Microsoft back in the 80s and 90s. I often referred to them a technology marketing company, not a development company. Still made gazillions on all that vapor ware. I am (was?) excited about CSM because internally my company has a separate team to support our external customers using the Zendesk support platform. it technically works, but has limitations. It's the part where they need to escalate to IT for support where integration suffers. So the idea of being able to merge support teams and share queues and handle external and internal customers alike on one platform, that is super appealing. Then again, maybe I just need to build my own mousetrap with what I have. We'll see. Ironically (sort of) I finally heard back from Atlassian regarding when I might see this magical mythical Service Collection appear in my tenant. Someone was nice enough to investigate and let me know that my tenant IS currently being converted over and I should see it in my tenant soon. Isn't that nice? And they were kind enough to sign me up for a 90 trial of the Jira Service Collection (prompting the CTO to ask me "what is this Jira Service Premium thing?). Fun times.