Black tie guest at a non black tie reception

Don't tell people how to dress. If he wants to wear a tux, it's really not your business. Clearly he will be over dressed but you have done all you should do.

I'd rather be overdressed than underdressed.

You could say "hey, no one will be wearing tuxes. I just wanted you to know so you weren't uncomfortable." But if he still chooses to wear one, that's his choice. Not really a bad thing, imo.

Over dressed is better than under- you can mention he might be a minority dressed like that- but no- you cannot say "don't fucking do that"

You can't tell him how to dress. If the BP are wearing tuxes, then clearly tuxes are OK.

Our wedding is pretty casual. Our groomsmen are wearing grey dress pants with a lighter grey shirt, suspenders (because he wanted them to... not me), and a tie.

My dad told me he was buying a nice suit and I laughed and told him he really didn't need to, and why. He said he still was going to because he doesn't get to dress up for his little girl every day.

You could bring it up again, and mention that he isn't expected to dress so fancy, but if he wants to just let him.

Take @bemyguests advice. That is perfect. It's not telling him what to wear, just informing him about what others will be wearing.

Don't tell adults how to dress. I'd rather be overdressed than underdressed. The last wedding I went to was an example of that. The bride's entire side was overdressed compared tobthe groom's, it was interesting.

Y'all are right, I can't tell him what to wear. I will mention it's really not dressy, as suggested.

My issue -- and why I want to (BUT WON'T!) say not to wear a tux -- is that other guests will think he's part of the WP. And be slightly confused.

But again, you're right that I can't tell a grown-assed man what to wear.

Everyone looks great in a tux....

I see random guys in tuxes almost every week. I don't think anyone mistakes them for the BP...

All the guys (including the groom) will be in linen khaki suits and one of our guests insists on wear a tux...I figure oh well if he wants to do that go for it

"... because he knows damned well that it is not going to be held at an elegant venue." Then he knows, and he follows the beat of his own drummer. No big deal. There's absolutely no reason for you to say anything to him regarding wedding attire. Some people dress according to their own standards. It sure as hell beats worrying about overalls and a T-shirt, right? Stop worrying. People don't judge the wedding couple when it comes to their guests' attire.

My FH wore a suit to a rustic casual wedding. I was MOH but told him he was overdressed. Didn't listen The complained he was the odd one out. But we were also raised to still dress up for dinner every night so atleast your guest won't be wearing crocs and a t shirt.

Is the wedding after dark? If not, wearing a tux is a fashion faux pas all around.

Edited to add: I'd rather someone be overdressed than show up wearing this:

He can always take his tie off. I can think of other things that bother me more.

I don't really see why people care? They come to show their support. Maybe I'm just easy going. I'll be happy everyone will be there. They know a photographer will be there so if they want to be photographed wearing blue jeans and a hoodie, then their choice. Don't even stress about it.

I mean unless it's super formal, there isn't much difference in a tux and a suit with a bow tie.

I mean if your BP was in jeans and he was in a tux it might be awkward, but otherwise I wouldn't stress. I think in general you try to hit within one deviation of the dress code, so a tux at a cocktail wedding fine. A tux at a backyard BBQ slightly awkward. Same thing vice versa a cocktail dress at a black tie wedding probably fine but a casual sundress may be a little too informal.

FH and I used to have this joke when we first started dating. I like to wear dresses alot (they're so easy). He would ask "Do you think you're going to be overdressed?" I'd always respond and say, "No, everyone else will most likely be underdressed." Obviously I was joking when I would say that but my point was I don't base my attire on what I think everyone else is wearing. Seriously, this isn't an issue. If the man wants to wear a tux no big deal.

My FIL'S have very fancy outfits picked out. Sequins for her and a tux for him. I tried telling them to just dress comfortably and our wedding is nothing fancy, but they aren't listening. It's their choice though I guess. Haha

H brother who was in our wedding party told me he was going to rent his son a tux so they could match. It was odd to me considering the kid was not in our wedding. I just told H brother that I bet he son would look cute but also that non of the other kids would be that dressed up. He decided against it. Does your guest think it's a black tie affair?

Is this really that big of a deal? At least it's appropriate attire for a wedding. You could mention that no one else will be that dressed up but at the end of the day it doesn't really matter.