Get two PDFs into a single email

One file for the letting agent by five o'clock

Lena is applying for a flat. The letting agent wants proof of income "as one PDF, please", and the viewing slot goes to someone else if it is not in their inbox by 5 pm. She has two files: payslip-october.pdf, a single page downloaded from her employer's portal at 180 KB, and statement-q3.pdf, nine pages from her bank at 14 MB because the bank pads every page with a logo image. The agent's office has warned that their mailbox rejects anything over 10 MB.

So Lena has three small problems stacked on one deadline: two files must become one, the order should make sense to a stranger, and the result has to squeeze through a mailbox that is stricter than her own. The sections below solve them in that order, and the same steps work for a cover letter and CV, a contract and its annex, or an invoice and its receipt.

Join the pair in the right order

Merge PDF handles this in one pass, inside your browser tab:

1. Open the merge page and drop both PDFs onto it, or pick them with the file chooser. They appear in a list in the order you added them, which is often alphabetical and often wrong.
2. Put the document the reader needs first at the top. Each file has small up and down arrow buttons; Lena moves the payslip above the statement, because the agent wants the salary figure before the transactions.
3. Press merge. The tool copies every page in your order, then reopens the new file and compares page count, page order, page sizes and selectable text with both originals. If that comparison fails, no download is offered.
4. Read the result panel. It shows the total page count and the size of the merged file beside the size of the originals, which is the number you need for the next step.
5. Download and rename. The file is named after the first document with "-merged" added, so Lena gets payslip-october-merged.pdf. She renames it Lena-Novak-proof-of-income.pdf before attaching it, because that name still makes sense in the agent's folder months later.

Will it get through the mailbox?

An attachment does not travel as raw bytes. Mail encodes it as text, and that encoding makes it about one third bigger. Many servers apply their limit to the encoded message, so a file that looks safe in your downloads folder can still bounce. Gmail caps a message at 25 MB, while company servers are often configured lower, and the receiving side can be stricter than the sending side.

The figures are simple arithmetic, not measurements of any provider. Lena's merged file sits at about 14 MB, so it would reach a Gmail inbox but not the agent's 10 MB mailbox. A practical rule: aim for an on-disk size around two thirds of the limit you are worried about.

Shrinking a merged file that is still too heavy

Compress the merged file once, after joining, not each part before. Open the compress tool, choose a target and let it work. Presets cover 100 KB, 200 KB, 500 KB, 1 MB and 2 MB, and any other cap can be typed in exactly; for a 10 MB mailbox Lena types 6 MB, which leaves room for the encoding growth. The tool tries several methods, keeps the smallest result that passes its checks, and makes sure text that was selectable stays selectable.

If a document cannot reach the number you set, the result says how far short it stopped and offers one more pass that pushes page images harder, with softer photos as the trade. Zipping is not a substitute: PDFs are already compressed inside, so a zip barely changes their size, as the guide to zipping PDFs explains.

Slip-ups that make the recipient write back

• The bank statement will not load. Many banks lock statements with a password, and the merge tool refuses locked files. Remove the lock first with the unlock tool, using the password you already have, then merge the unlocked copy.
• A signed contract lost its signature check. When pages are copied into a new file, a digital signature does not come along in working form, and the tool warns about signature fields before it runs. Send a digitally signed PDF as its own attachment.
• A filled form went blank or stiff. Interactive fields may not stay editable after a merge. Flatten the form first so the typed answers become part of the page.
• Pages arrived in the wrong sequence. Scroll through the joined file once, paying attention to the point where the second document starts. A missing last page or a doubled cover is easy to spot there.
• The file name told the recipient nothing. Names like scan0042-merged.pdf get lost. Put your name and the contents in the file name, and mention both documents in the email text.

When two attachments or a link is the better call

One file is not always the kind option. If the recipient uploads documents into a system with a separate slot for each one, such as a visa portal or an HR onboarding form, merged files force them to split your PDF again. Ask before combining. Digitally signed documents, as noted above, should also travel on their own.

Size is the other reason. Once the combined file stays above about 20 MB after compression, or you are sending a whole folder of documents, a download link causes fewer problems than any attachment; the guide to sharing a PDF by link compares the places that can host it. And if your employer forbids web tools for client files, follow that rule even though this one runs locally, and use the software your IT team provides.