How to appropriately send a wedding gift in the form of a check is by addressing it to either the husband or wife.
This will enable them to cash it, instead of getting a bounce at the bank due to a conflict in account details.
If you have the urge to add a complimentary message, then pen it down in the part of the check allocated to comments.
It is very wrong to address a joint check to newlyweds using their new surname. That is an assumption on your part as you don’t know if they will retain their individual names.