Different people have different systems for keeping track of their mail. Misty Davis posted about her system here. Still, she continues to have a bit of trouble knowing which items have been responded to and which still need answering, etc.
Let me tell you about the system I use to keep up with my incoming and outgoing mail. I base it on a system I perfected years ago for my sewing, crafting, and crocheting projects. My main problem then was that so many of the things I wanted to keep track of fit into more than one category. For example, I had a crochet heart pattern that used red, white, and blue yarn and resembled an American flag when completed. Would I file it under crochet, or hearts, or Patriotic/4th of July??
Do you see the dilemma? No matter which category I picked, I was afraid I wouldn't remember it could be an option in the others.
After much trial and error, I finally worked out a system that made sense to me and was manageable. I could locate instructions for any pattern in seconds. And that was the goal, after all. I catalogued all of my items with a simple numbering system, 1, 2, 3... New instructions were labeled with the next number and everything was filed in numerical order.
Next I made an index file with cards for each type of craft or activity. Birthdays, Christmas, Crochet, Hearts, Patriotic, Valentine's Day, etc. Say item #32 was that crocheted heart I mentioned above. On the index cards for Crochet, Hearts, Patriotic, and Valentine's Day I'd list #32. That way it could be filed in several categories all at once.
Conversely, if I wanted to make a heart, I could pull out the heart index card and find all projects that dealt with hearts listed by number, so easy to find. Oh, and to jog my memory, I typed up a master list, also in numerical order with a description of each item so I didn't have to dig through the actual files. Does that make sense?
I have a similar system for my mail log. All my correspondents are listed by name on individual index cards. The card contains name and address, email, and website info. Sometimes I include the person's birthday if I know it and a few notes about their hobbies or interests. Every time I receive an item from that person, the number of that item of mail gets written on his/her card.
As I open the day's mail, I assign the next numbers in sequence to each new item of mail. I also note the date it was received. Next I update each person's index card with the newly assigned numbers. As I answer back to each item, I list that on the envelope as well. If I want to locate all the items of mail Misty has sent me, I simply pull her index card and fish out the numbered items from the files.
Works for me. If you have any questions, I'll be happy to try to answer them.