I recently married and got quite a few congratulatory cards. However, I didn't get any message from a couple that is friends with my parents and usually congratulates me for everything (birthdays, job changes etc.). I know from my parents that they are very happy for me and were talking about it, so they definitely know (and approve) of it.
Since I am currently writing thank-you notes to all the well-wishers, can you think of a subtle way I could find out if they sent a note which might have gotten lost in the mail? (German mail ain't what it used to be!)
Additional info: This couple lives in the place where I grew up, I didn't specifically talk with them recently or about the wedding, since I haven't been home for a while, although they did congratulate me for my birthday just a month before. I feel like asking them personally would put them on the spot in case they just forgot. On the other hand, I would not want them to miss our thank-you notes (we make them by hand, personalized, fitting to the sent note and/or wedding present and send them by mail, my wife is very adept at decorating them so I wouldn't want anyone to miss out) if they actually did send a note!