How to Send Multiple Letters at Once to Different Addresses

To send multiple letters at once to different addresses, first answer one question: does the letter itself change from person to person?

If every letter is different, such as twelve thank-you letters your CEO signed one by one, each is its own PDF, and in Postmarkr they go in the Cart: up to 10 letters, one checkout. If it's one letter going to a list, such as a year-end letter to clients, that's Bulk Send: one letter, a CSV, up to 100 recipients per batch.

Either way, nothing gets printed at your desk, stuffed or stamped, and every letter keeps its own record. Most of the work is getting the address list clean, which is the last section.

Same letter or different letters? Decide first#

Put two of the letters side by side. If only the address and maybe the greeting change, it's one letter going to many people, and Bulk Send mails it from a CSV. If the paragraphs differ, they're different letters, and each goes in the Cart as its own PDF. How to automate mailing letters from a spreadsheet has the full table, including the case where letters need to send themselves from your software.

Send different letters to different people: use the Cart#

Say your CEO comes back from a conference with twelve thank-you letters, each personal, each signed. Here's how they go out together.

1. Save one PDF per letter. If they came back as one long document, split it into separate files first. Postmarkr mails each uploaded file as one letter; it doesn't split a combined file for you.
2. Get each one signed before you upload. We print what's in the PDF and can't add a signature. If you sign for your executive, how to sign a letter on behalf of your boss covers p.p., initials and when not to.
3. Start a letter, upload the first PDF and pick the recipient and a return address, usually your executive's office. Check the preview: it shows the letter as it will print.
4. Choose "Add to Cart to send several together" instead of paying. Repeat for each letter.
5. Open the Cart and pay for up to 10 at once. Twelve letters take two checkouts: ten, then two.

Each letter is priced by its own page count. A one-page black-and-white letter is $2.05 all in (printing, the address page we add, the envelope, First-Class postage and the processing fee), and two pages are $2.26. Twelve one-page letters come to $24.60. Pay within six days of uploading; after that, a PDF has to be uploaded again.

After payment, each letter has its own status page. Check its milestones for progress, and download the production PDF once it is available. A payment receipt alone does not show that USPS has the letter.

One letter to a whole list: Bulk Send, in short#

The year-end letter to clients, an office-move notice, the service-anniversary letters HR asked you to handle: one letter, many people. Bulk Send takes one shared PDF when nothing changes but the address, or a letter template when the greeting or a detail changes, with each person's values filled in from a column in your CSV. A batch holds up to 100 recipients and $1,000, with one return address for the whole batch, so a list of 180 clients goes as two batches, 100 and 80, for $369 in one-page letters. For the steps, from merge fields to the proof, read how to automate mailing letters from a spreadsheet; prices and limits are on how Bulk Send works.

Get the mailing list ready before you upload#

One EA described the usual state of things on r/ExecutiveAssistants: "My exec keeps several excel lists of people/addresses for different purposes — one for holiday cards, another for gifts, another for events ... I'll update one and forget to update one of the others." Fix that before any batch. Mail returned as undeliverable because of an incorrect or incomplete address isn't eligible for a refund or a free resend.

1. Make one source sheet. Combine the three lists into one, with a column for what each person is on: holiday, gifts, events. That's the fix other assistants suggested in the same thread. For each mailing, filter the master and save the result as a CSV. Next year you update one sheet, not three.
2. Use the columns the upload expects. The spreadsheet guide lists them, and the sample CSV in Bulk Send supplies them.
3. Format the ZIP column as text first. Excel drops leading zeros, so a Boston ZIP like 02116 becomes 2116, and a four-digit ZIP is rejected. Format the column as Text, or use a 00000 custom format, before the addresses go in. Formatting afterwards won't bring the zeros back.
4. Remove duplicates yourself. Bulk Send catches exact repeats of the same name and address, ignoring capitals and spacing, across your CSV and your saved addresses. It can't tell that "Pat Smith, 12 Oak St" and "Patricia Smith, 12 Oak Street" are one person. Decide, too, whether a couple at one address gets one letter or two.
5. Read the address-check result. The address check reports a USPS/Lob deliverability result; it does not confirm that the recipient still lives there or guarantee delivery. Review the rows it flags, correct the addresses and upload again. Confirming current addresses belongs in your year-end routine.
6. Keep the clean list. Valid CSV recipients are saved to your address book when you send, so the next single thank-you letter starts from a saved address. You can also import the master sheet into the address book ahead of the season (up to 500 rows per file) and check every address at once.

Questions assistants ask#

How many letters can I send at once?#

Up to 10 different letters per Cart checkout, and up to 100 recipients and $1,000 per Bulk Send batch. A longer list goes as several batches.

Can Postmarkr mail our holiday cards?#

We don't print cards, use card stock or write by hand. We mail printed letters, so a year-end letter on your executive's letterhead is the closest thing we can send.

Will a merged letter look personal?#

Each letter carries the recipient's name and any details you merge in, and the signature prints from the image you add. The envelope is a window envelope showing the address page, not a hand-addressed one.

Can I set the batch to go out on December 1?#

There are no scheduled sends. Prepare the batch whenever suits you, then pay when you are ready to start processing. Allow the next business day for printing and plan ahead for USPS's estimate of 1–5 days for First-Class delivery.