It's been a few years since I've done mass-mailings, but it's easiest simply to stick to Microsoft Office - stick all the data in an Excel spreadsheet or Access DB and mail-merge it into a Word document. OpenOffice probably has the same features if you don't have MS Office already, and that's a free download.

Then get a local printing company to run up a batch of windowed envelopes with your logo and return address (so much easier than printing the envelopes as well). Either use a postage meter, or if the volume justifies it then get the postage pre-printed (speak to your local postal authorities for details).

Using a machine for envelope-stuffing is only worthwhile if you have very high volumes of mail, otherwise just get a student or two in for a couple of hours of easy work, or rope in some family members or split the work between co-workers. ;)

Thank you for the advice, it was very helpful.

What if I did have to print directly onto the envelopes? Specifically, thick professional envelopes? My mere inkjet printer right now cannot handle them and always gets jammed.

A decent laser printer can handle envelopes, but if you want color then you're going to have to spend a lot of cash for it. What's the speed of your inkjet? Is it robust enough to handle large printing jobs? A color laser may be required for the contents too, the printers are more expensive but the ink is less so, so you need to calculate costs carefully.

If you print addresses on the envelope then you have to make 110% sure that the name on the envelope matches the name on the letter inside - so stuffing the envelopes is much slower.

If you look at some of the bulk mail you receive from other companies, you will find that nobody personalizes the envelope - too much hassle. If you can't use windowed envelope you can print address labels instead of putting the envelope through the machine, but it's slow manual work in addition to the envelope-stuffing. So, in short, do what you can to avoid having to print envelopes!

If you look at how much it costs for a decent run of windowed envelopes printed up with your logo etc by a local printing firm, you'll probably find that printing your own envelopes is not cost-effective anyway.

Thanks for all of your input!

One last question: if I were to scan in my signature and just print it out on the letter (versus hand signing each one), will this look realistic? I am really looking to automate as much of this as possible.