You upload. You approve. We produce. You upload the letter as a PDF, Word file or image, plus a spreadsheet list. You check the proof on screen, pick the mail options and see the full price. Then you approve, and we print, stuff and mail. The steps are spelled out on Upload. Review. We mail it..
Every address comes from you, and we check every address before mailing. That check doesn't promise when or whether a letter gets where it's going. A line that doesn't match a USPS address is flagged so you can fix it before you approve. From our own production floor: we print, envelope and hand each piece to USPS, and you see the proof and the full price before you approve.
If plans change, you can unapprove an approved job before its mail date, and unapproving puts the money back on your meter, not your card. A meter balance is optional, and you can pay per mailing.