I address the box or envelope as soon as I get my partners name and address. On the outside of envelope, or box ,I label and tag it with the swap. You can also put due date on back. Example FQ Feb Swap SP Feb swap NC/PC Feb Swap Mug/Rug Feb Swap. You can put the print out of the swap, or a reminder note of what you want to send in it. You can add things into it, until you are ready to mail. I have a bin I put them , until I am ready to mail. You can request free boxes , padded envelopes , and your mailing labels, free of charge through the mail. You can also purchase pre paid postage envelopes and boxes , then just hand them to your postman.