Around this time of the year, I start to receive questions like "can I send save the dates out with my holiday cards"? and "How to I mail save the dates out with my christmas cards?"
Can you? Yes. But... you have to make sure that you send save the dates in ONLY with those family members that are sure to receive an invitation later. "Save the date for my wedding" does not equal "announcing my engagement". If you want to stick with just announcements, those were around long before save the dates were.
How do you? Well, if you are getting a save the date card and a holiday card, it's as simple as putting both in the envelope. If you are getting magnets, though, and the card isn't the same size as the magnet, you could end up with the magnet edges scratching the card in transit- doesn't look the best. Two options are to make your card so that part of it holds the magnet, or to include the magnets in their own little envelopes.
Slits or photo corners with a folded card that is printed with a holiday message would work well for a holder holiday card.
There are mini envelopes available for both the 2x3.5 inch and 2.5x4 inch magnet sizes. These smaller sizes are problematic for mailing on their own- you can't mail anything out that is smaller than 3.5x5 inches with the US postal service. But included inside another envelope? Perfect.
Save the Date Originals is preparing the holiday section right now... those who order either the 2x3.5 or 2.5x4 inch save the date magnets with holiday cards get mini envelopes for free.
No, your save the date doesn't *have* to be christmas themed either. If your wedding is actually going to be the following winter, that works out well, but otherwise, go with the colors and theme that you would normally go with.