When your card goes in the post it will pass automatic sorting machines that have a series of guide rollers. It may be turned around sharp bends and squashed in the franking machine. Not to mention the rough time it may have in the mail sack.
If your delicate stitch work or bead work has only the paper envelope to protect it there is a good possibility that it may suffer. You could put an extra sheet of card over the work surface but these days the UK post office makes an extra charge for thick envelopes.
There is a simple solution that does not involve any extra padding. The answer is to turn the card inside out before you put it in the envelope. That way your embroidery and any other ornamentation is safely out of harms way.
When you do this it is worth putting a small notice in with the card telling the recipient what you have done. Otherwise they may come to the conclusion that you have made the card inside out deliberately.
How do you protect your cards in the post? Let me know by adding a comment to this post.