Does anyone know the purpose of the "group email' in group properties

I thought it might be an email common to everyone in a group so that via one email address you could contact everyone in the group, but this didn't make sense.
Any ideas?

yes that is the purpose. It presumes that group maling lists are your responsibility. It appears somewhere on the UI to let you email the group via some external maling list or similar.

To be clear, this is just a text box containing the group email, correct? So from Plone, this email can't do anything.

If so, then, I see this as a potential for a UI improvement (you call them bugs). Looking at the UI, there is no way to know this is just a placeholder for the group email, to allow you to do something with it, outside of Plone. It is reasonable to assume it has functionality.

I suggest quick words be added next to this box, like "This group email is manged outside of Plone" .

Of course, there is the question, why can't it function? Plone has the smtp configured, so this email could be used within Plone to send email to the group.

it does function somewhere but I forget where. I suspect there is some place on the UI where it mentions the group and gives you a link to email the group in the same way as you can email a user. One place its used is the contentrule to send to a group.

I think the issue you've identified is that "its confusing when creating a group the email field is used for". There are multiple ways to fix that. A better description might be one way that also might get used for other things over time so could get out of date. Another way is we remove it and handle all group emails by mailing every member of the group.

I think your second option (email to everyone in group) makes the most sense. I've hired someone to get the old P4 'mail to group' to work on p5.

having a second email for the whole group means one more email people have to monitor. if some don't (and they won't), then they are out of the loop.

I suggest we get rid of the group email address. I think it sets false expectations (as it did for me)

what do you think?