...
Related to message data, JEMHC does support inline images in outbound notifications, and attachments, if you enable this, and make regular use, it can impact your data usage.
MailserversMail servers
JEMHC cannot use the mailbox provided by Atlassian, you must use an external one, when doing so you may need to refer JEMHC public IP address to allow contact to your instance - this allows anyone on JEMHC to attempt this, for finer grained security, you would need to setup dedicated certificates that only your configuration has.
Microsoft office 365 (in:POP/IMAP/EWS, out: SMTP)
Gmail (in: POP/IMAP, out: SMTP)
Your own dedicated Exchange server (in:POP/IMAP/EWS, out: SMTP)
New users start on a Starter Plan that is deliberately limited in capacity, this is to fail fast when problem scenarios occur (e.g. processing a POP mailbox where the ‘from now’ checkbox wasn’t set…)
What's missing?
...
Scripting support
There is no Script Field Processor or Script Project Mapping Rules yet. This is a big feature to do for cloud and is something we hope to look at this year.
...
For inbound, Jira project metadata defining fields that we need to populate. For outbound, we retrieve any data within the typical REST response for the issue, eg e.g. /rest/api/latest/issue/ABC-123. In addition, attachment data referred (eg e.g. inlined screenshots, but could also be any attached file, if you configure JEMHC to do so!), icons for projects, issue types, priorities, all the things you’d you'd expect in a Jira email.
Is it data in transit or data at rest?
...