If a card publisher does not accept design submissions digitally, here are some tips for sending your designs the the U.S. mail.
A simple, inexpensive way to reach out to different card publishers, is by compiling a a folder of your designs. Make a practice of doing research, selecting your ideal companies, and then mailing out a packet periodically. Try to Include the following items, and remember to put your contact information on every item in the folder.
1. Any articles or ads about you and your art.
2. It's nice to show a photo of your cards in a group on a shelf. If you don't have a card rack, visit a local store and see if they will give you permission to do a quick photo of your cards on 'their' shelf. Give them your samples to keep as a thank you gift before you leave.
3. Glossy pages with photos of your card line. Include 3 or 4 of these sheets if possible. You could put a different "family" of designs, with the same look, on each sheet. (Christmas, Spring, Pastels, etc). You can also include an artist statement or short resume in this section.
4. Real card samples.
5. Glue on business card (versus sticking it in tabs). They won't fall out and it looks more attractive.
6. Instead of typing up a formal introduction, paper clip a handwritten note on card stock. People are more likely to read a quick personal note rather than a long intro letter.
7. If possible, include a CD of your card images. Label with name, contact information, business name and card line theme (floral, humor, birthday, etc). Put these in jpeg or low resolution formats, so they don't get accidentally forwarded by email and then printed by someone you don't know.
It's easy to make a sticker, or glue on a piece of paper onto the front of your folder to make it look attractive. You don't have to pay to have them printed. Print a dozen from your computer.
Use a glossy folder, and avoid flimsy thin paper folders. Also avoid folders with spine clips, unless you plan on converting your folder into a book style portfolio.
If you have a lot of design ideas, and don't want to flood your folder with too much paperwork, you can scatter cards on the table, photograph it, reduce the size and print it out on a 8 1/2 x 11 sheet of glossy photo paper.