Ahh, I was just about to start a post about this. I just blocked someone I don't know, after getting double invites 4 days in a row. (If it isn't a friend, you can't message them I think) Please realize that if someone declines your invitation, that means they don't want to join the group. They aren't likely to change their mind if you keep sending the invitation repeatedly for days. It doesn't matter what the reason is, spamming and harassment isn't going to benefit your project.
Yeah, I wasn't going to say anything, but now that you've already started the topic...
This is quite annoying. If you can send a person multiple invites, you know they've been declining your invites. Just don't invite one person more than once - we're probably not going to change out minds in 12 hours. And yeah, I know, if I don't decline then they can't send me another invite, but I'm kind of compulsive about clearing my notifications - I'm sure I'm not the only one.
TL;DR - don't invite the same person twice, they've already declined!
Just offering my experience here, and not forcing anyone to adopt my view. I always feel more inclined to be receptive to an invitation to a group if someone were to approach me first either in IM or a message and just chat with me about their group and their cause. I don't normally like having an invitation thrust upon me without having someone chat with me first, maybe that's just me though. *hugs* and Cheers :D
Whilst I find it annoying too, I think the repetition of invites, for at least the second request, has more to do with the person forgetting whom they have invited and whom they haven't invited. For once a person has declined an invite they no longer appear in the group list as 'invited' and nor obviously as a part of the group. Therefore the group owner may send out a second request just in case they accidentally skipped over that person in the first round, and wouldn't want to offend the person on their friends list by not inviting them.
However, this is only applicable for a second request, and even this double up could be done away with by the installation of something that records declined invites too. As for invites after the second one, I say block them.
Here's a possible solution which shouldn't be too hard to implement: when you get an invitation to a group, you can click through to the group's page. Next to the "Join this group" button, there could be a "No invitations, please" check box. Check it, and your name would be greyed out on the invitation list. You'd be able to un-check the box if you wanted to join later.
I have my own groups, so sometimes you don't realize how many times you invited someone :) there should be something that shows how many times you've invited specific people
I made only one group ever, and I couldn't figure out why certain people were not selected when I could have sworn I already sent them an invite. . . . duh! They denied! Case closed, but I didn't realize that at first and probably sent people several invites. I'm sure it would happen less if people knew.
I'm sure many people aren't aware of the inconvenience. I notice that most frequently when i received group invitations, it was multiple friends who belonged in the same group so they would have no way of knowing that i already declined. (In fact, they probably thought something more like "Oh wow i can't believe you're not involved yet!") As WindBorn stated, if you just leave the requests in your pending you won't be invited any more, which is a good way to handle it for now! Glum's idea is fantastic and i hope it has been posted in ideas! (heading over to check now...) =^.^=