Warn on Reply All

Objective

Warn on Reply All if...

1. No recipients have been added/removed from the To or CC fields,
2. The default behavior is not Reply All; we don't want to nag on the normal workflow.
3. There's more than one recipient in To and CC combined.

Testing Notes

Ensure that the warning appears just before sending only if the Reply All recipients are in the To and CC fields, with no additions or removals.

Tips

I've started this already in the branch codemouse92/replyallwarn, but I'm running into a roadblock trying to get the message being replied to so I can call participantsReplyAll on it again. Insight appreciated, @bengotow!

References

https://community.getmailspring.com/t/reply-all-popups-before-replying-to-multiple-people/912