This problem affects all email List users, because if not solved, Groups.io becomes less effective when subscribers/members unexpectedly are unsubscribed.
The responsibility to educate individual email List users should not be on individual groups owner, who will not all do so (if at all) in a clear and rational way.
The fact that questions about this keep coming up on GMF, says that many groups owners and subscribers/members aren¡¯t clear about this.
I say in my Welcome Message to new subscribers (although this is probably not enough):
If [groupname] messages are misdirected (probably by your Email Provider) into your Spam and/or Junk folders: DO NOT DELETE THEM, MOVE THEM TO YOUR INBOX - Marking and/or deleting [groupname] messages as SPAM or JUNK can send an automatic "Unsubscribe" command - this is a new anti-Spam mandate that is being adopted by Email Providers.
Email List group providers, such as Groups.io, are in the best position to do it well and for all Groups.io users. Groups.io could send a monthly (probably more frequent) Special Notices asking users for their help (including explaining WHY) and telling users to be sure to (and HOW):
-Not to mark any Groups.io message as SPAM or JUNK (even if it is a SPAM post and/or from a hacked email address, but to report to their group owner).
-Check their SPAM / JUNK folders regularly (daily or weekly) - just as you would your US mail box for physical, ¡®postal¡¯ mail.
-Not to delete any Groups.io message marked as SPAM or JUNK.
-Not to let their Email Provider automatically delete any Groups.io message marked as SPAM or JUNK
-That they may get Unsubscribed for this
-What to do if they get Unsubscribed
Groups.io should be sure to explain WHY and HOW (in non-computer savvy language), not just refer what seems to many to be a cryptic Wiki. Pictures and/or videos might be useful.
The test is not ¡®does it make sense to those in the know¡¯ but does everyone (who doesn¡¯t know about this) understand WHAT and HOW it is said. (I suggest non-computer savvy people should proof read this and be assessed for their understanding).
Michael Pavan