marc33 wrote: It works from my personal Gmail account (made myself an other officer)!
Our club has its own Gmail account (quest4643@gmail.com) and I tested sending an email to library@questtoastmasters.com from there (with just my name/email selected as a person in the Library group so I would be the recipient). I set up "Guest" as an other officer in our Members group with the email address quest4643@gmail.com. The email bounced with this error message: "You do not have the right permissions to send an e-mail to this e-mail address (library@questtoastmasters.com) from quest4643@gmail.com . Be sure your "From" address in your e-mail client is the same as your address in your toastmastersclubs.org member profile.".
What am I missing?
Keep in mind that even though you have set up a custom group, the sending rules for who can send to a non-member are still enforced. The sending address must belong to a member who is also marked as an officer in Membership Management. This is checked by the list server code. In fact, it determines if the group is a member only group or a non-member group and changes how it enforces the sending rules based on that.
This is also why groups cannot be mixed ... cannot contain a mixture of "people types" from multiple Membership Management tabs. This is so that the sending rules for the corresponding email addresses can still easily be enforced. If groups could be a mix of members and non-members, it would be unclear who would have the rights to send to such a group.