Existing Documents (ZIP Upload)

If you already have individually prepared PDFs or DOCX files — for example, certificates generated by another system — you can upload them as a ZIP archive. MergeMail will match each file to the correct recipient and attach it to their email.

When to Use This Mode

• You have a batch of pre-generated, individually named PDF certificates.
• You received signed contract PDFs that need to be sent to each signatory.
• Another system generated the documents and you only need the email delivery part.

If you want MergeMail to generate documents from a template, use the DOCX/PDF template mode instead.

Preparing Your ZIP Archive

1. Name each file in a way that can be matched to a row in your spreadsheet — typically using a unique identifier like email address, student ID, or name.
2. Place all files in the root of the ZIP (not in subdirectories) for best results.
3. The archive may contain PDFs, DOCX files, or a mix.
4. Maximum ZIP file size: 200 MB.
5. Maximum files in archive: 5,000.

Recommended File Naming

• adaeze_okonkwo.pdf — matched against the full_name column.
• CERT-0001.pdf — matched against a certificate_id column.
• adaeze@example.com.pdf — matched against the email column (highest confidence).

Matching Logic

MergeMail uses a scoring algorithm to match filenames to rows:

1. Exact email match — If the filename (without extension) is an email address that appears in the email column, it is an exact match (confidence: high).
2. Exact ID match — If the filename matches a value in any column exactly, it is a high-confidence match.
3. Normalized name match — The filename is normalized (spaces→underscores, lowercase) and compared against normalized column values. Partial matches score lower.
4. No match — Files that cannot be matched are listed as unmatched. You can manually assign them.

The Matching Preview

After uploading the ZIP, the Matching Preview screen shows every file alongside its matched recipient row and confidence level. You can:

• Accept auto-matches and proceed.
• Manually reassign a file to a different row.
• Mark files as "no attachment" for rows where no matching file exists.
• Remove files that do not belong to any recipient.

Security Constraints

For security, MergeMail enforces the following on ZIP uploads:

• File paths that use ../ path traversal are rejected.
• Executable files (.exe, .sh, .js, etc.) inside the ZIP are rejected.
• ZIP bombs (highly compressed archives that expand to large sizes) are detected and rejected. The decompressed size limit is 500 MB.
• Only .pdf and .docx files are processed; all other file types in the archive are ignored.

Manual Override

If automatic matching fails for a row, the recipient still receives an email — just without a document attachment. Use the matching preview to manually assign the correct file before launching the campaign.