How do you get money in the mail?
Start with your cause. 
What is a story you know needs to be told?
What are some facts to show you're doing 
good work?
Once you have gathered your story, your statistics, 
now talk with some well known people in your community. 
Would they be willing to be quoted in your letter? 
If so, ask for a picture, write the quote or blurb for them and ask them to approve it.
Now put your hands on your mailing list. Whether you've got 20 names or 5,000 names, you've got something to work with.
Put your letter together.
Start with the story
Put in the statistics
And end with a picture 
and quote.
Go to your mailing list 
and put it into a spreadsheet.
In many database programs, 
this is known as EXPORTING.
Name each column, first name, last name, address, city, state, zip.
Now go to your letter. Put in database fields at the top of your letter
It should look like this:
<firstname><lastname>
<address1>
<City><State>
<Zipcode>
Now add a Salutation.
Be sure to personalize it.
Dear <firstname>,
works well.
Now you're ready to Mail merge!
If you're running 
Microsoft Word, they've got a Mail Merge Wizard that will walk you through the process.
Once you've done merging,
You should have a prompt to
open a new document.
This document has all of 
your letters, all 20 or 5,000 
of them. 
It's worth your while to go through and make sure each letter is correct. If you know some of these people, personalizing it a little bit works well too.
Now you're ready to print your letters. Make sure the letterhead is in the printer, with the correct side facing up. 
Once your letters are printed, you can print your envelopes.
Make sure your envelopes are facing the correct way in the printer, and print your envelopes.
Now comes the fun job of
putting the envelopes together with the letter.
Ideally, you want to get volunteers to do this. It's a mindless task.
If your nonprofit has a nonprofit mailing number but no indicia yet, now is a good time to put it into your envelope template. You can create one with a text box feature.
Once your letters are inside the envelopes, if you don't have a remit envelope, It's time to arrange the envelopes in zip code order. If you have them in Alphabetical order by last name, sucks to be you!
Sort your spreadsheet by zip code. This will save time later.
Now it's time to take your letters to the post office! VROOM! You'll need strapping material, which you should look up online how to find in your area.

(Top tip: You know the best time to go is NOT Friday, NOT at 4pm. That's when everyone is going nuts there. Go on a Tuesday afternoon.) 
Now you're at the post office!
You need to weigh your envelopes, zipcode by zipcode. The first 3 numbers of the zipcode are all that matter, and write down how many letters of each zipcode that you have. 

If you have less than 150 of a certain zipcode, you can't get a bulk mail discount. 
Now you've got to put
the envelopes in trays, put cardboard sleeves on the trays
put strapping around the sleeves, And get those trays to the post office clerk.
The clerk will weigh the trays, and you should have the nonprofit credit card ready to go to pay. Or have the money already in the account.
Put a little label for the zipcode on the front of the tray. (The post office provides these)
Celebrate! You're Done! 
Now watch the money come in.
Let's go through, step by step, how to write an appeal letter. This will help your cause get the money you need! 
Keep track that you mailed this letter to these people in your database. 
Create a new document. Choose paper type as Envelope. Make form fields as before(<firstname>
<lastname> etc)