Compress, Merge, and Send a PDF Workflow

Sending a PDF by email is usually the easy part. The hard part is getting it under the attachment limit. Gmail caps attachments at 25 MB, Outlook at 20 MB, and many corporate mail systems are tighter still. When you have several PDFs to send and the combined size is over the limit, the workflow is: compress each file, merge them into one, compress the result, then send. This guide walks through each step using IXPDF's local tools — your file never leaves your device.

Why this order: compress → merge → compress

Compressing before merging gives you smaller inputs to merge, which makes the merge faster and the merged file smaller from the start. Compressing after merging catches the structural overhead that merging can re-introduce (each merged file brings its own font and resource dictionaries, which a final compress pass can de-duplicate). The two compress passes are cheap and lossless — there is no reason to skip them.

Step-by-step: the compress-merge-send playbook

1. Compress each source PDF. Open/tools/compress-pdf/, drop in the first file, and click Run Compress PDF. Note the compressed size. Repeat for each file you plan to send. Save the compressed versions with clear names (e.g. report-compressed.pdf) so you can tell them apart from the originals.
2. Merge the compressed files. Open/tools/merge-pdf/, add the compressed PDFs in the order you want them to appear in the final document, and run merge. The result is a single PDF containing all your pages in order.
3. Compress the merged result. Drop the merged PDF back into /tools/compress-pdf/ and run compress one more time. Merging can re-introduce structural overhead because each source file brings its own copy of shared resources — this pass de-duplicates them.
4. Check the final size. The results panel shows the size. If it is under your email limit (25 MB for Gmail, 20 MB for Outlook), attach it to your email and send. If it is over the limit, see the fallback below.
5. Send. Attach the final PDF to your email and send. No upload to a third-party service, no link to expire, no account required.

Fallback: what if the merged file is still too big?

If the merged, compressed PDF is still over your email limit, you have three options, in order of preference:

1. Split and send in two emails. Use/tools/split-pdf/ to break the merged file into two halves. Send each half in a separate email with a clear subject ("Report — part 1 of 2"). This keeps everything local and avoids any link-expiration or account requirement.
2. Remove pages the recipient does not need. If the document has appendices, cover sheets, or blank pages, use/tools/remove-pages/ to drop them before compressing. Fewer pages means a smaller file.
3. Re-export from the source with lower image quality.If the PDF is image-heavy and compression is not enough, the most effective lever is to re-export from the source application with lower DPI or JPEG quality. This requires access to the source file and trades quality for size — use it as a last resort.

Tips for specific cases

• Scanned PDFs are the most common size problem. They are essentially one large image per page. Compress helps a little; re-scanning at 150–200 DPI helps a lot. If you cannot re-scan, splitting is usually the right call.
• Multiple versions of the same document — do not merge them all. Send the final version. If the recipient needs the history, send a follow-up email with the earlier versions.
• Documents with embedded full font sets can be much larger than necessary. If you can re-export from the source with subsetted fonts, do that before compressing.
• If you are sending to a corporate mail system, the effective limit is often 10 MB or lower. Compress aggressively and split if in doubt — a bounced email wastes more time than a second email does.

Common mistakes

• Merging before compressing. It works, but you miss the chance to give the merge smaller inputs. Compress first.
• Skipping the second compress pass. Merging can re-introduce overhead from each source file's resource dictionaries. The second pass is cheap and catches it.
• Using an online "compress and merge" uploader for sensitive documents. That uploads your file to a third-party server. IXPDF does the same work locally — your file never leaves your device.
• Sending a 24 MB file to Outlook. Gmail's 25 MB limit is not Outlook's. If you do not know the recipient's mail system, target 20 MB to be safe.