You can send automatic auto-reply emails to senders of incoming emails, auto-replies can be fully customized and the sender's email address is saved to a custom field.
Add JETI Post-function
It is strongly recommended that JETI post-function is added after the system post-function called "Re-index an issue to keep indexes in sync with the database." in the list of post-functions of the transition. This will make sure that the updated attributes are included in the emails.
You can add multiple JETI post-functions with different JQL filters to implement complex conditional logic.
Configure email attributes
You can configure email recipients, content and options for the post-function the usual way. . You may add recipients from a user picker custom field from the recipients' list by selecting them from under "Recipients stored in field".
Note, you can specify to append the comment entered during the transition to the mail body. If you do not configure the post-function with a mail body value, you can entirely rely on the comments as mail body.
Email options are prefilled with the global default values.