My advice is to NOT use a single message to weed out people from the potential guest list. And it sounds like the OP is, in fact, going to follow up with people, so good.
Story: This happened to my friend Amy. Our mutual friend Mike was getting married and sent out emails saying, "We want to invite you to our wedding! Please send us your address." I got one and replied promptly (and later received an official paper invitation). Amy's message from Mike went into her junk mail, for some reason, which she didn't discover until just a couple weeks before the wedding. Mike never tried to contact her via another method, so she ended up not being invited to his wedding, although she would've loved to go.
Not being able to attend wasn't the end of the world, of course, but she was a little hurt that he didn't try harder to reach her, when it's so easy for just one message to go astray. And why would *I* get an invitation and not her, when even in my own opinion, she and Mike had been closer friends? I think for her it was one of those painful moments when you realize the other person doesn't feel as close to you, as you do to them.
Actually the situation was even weirder. In reply to the initial email I asked Mike if he was inviting anyone else I knew, so I could look into carpooling, and he said "maybe" he would invite Amy. Trying to be polite and discreet, I never mentioned the email to Amy--if I had, she might've looked for her own message sooner! A couple weeks later, Mike asked me
for Amy's address, but cautioned that he still wasn't sure if he'd have room to invite her--so she was B-listed, I guess. And then there wasn't room for the B-list, so she actually never heard a word from Mike about his wedding, after the first email that went to junk.
The thing I thought was a bit tacky was that his initial email specifically said, "We want to invite you to our wedding." So he threw the idea of the invitation out in front of people. I feel like once you do that, you have an obligation to exert reasonable effort to track the person down and, in fact, officially invite them. To me it's the same idea as sending a Save-the-Date to someone, then not officially inviting them, which I gather is rude. The email wasn't, "We are currently conducting a screening process to determine our guest list. Please respond if you would like to be included and we will take that into consideration." (How horrible!) It was, IMO, "You are on our guest list. You have been invited
. Please help us figure out how to get more information to you as it becomes available." But maybe that's just a matter of interpretation?