How to Combine Split Base64 Encoded Attachments

How to Combine Split Base64 Encoded Attachments
h2. How to reassemble an attachment split across several emails.


When using a digital sender to scan documents, such as a Lanier Copier or otherwise, there may be a setting that divides a particularly long E-Mail attachment into several files. This is especially true when the size of said PDF scanned file exceeds a size limit, such as a 10 MB limit.

In such cases, the scanned file will send as two separate attachment files, however it will be encoded in a Base64 string.

Compiling and Decoding the Base64 Fragments

  1. Download the individual attachment files (make sure the proper order is assigned, so you may want to rename each one “document-1, document-2, etc”). They can be saved as .txt if you wish.
  2. Concatenate the files in DOS, using the command copy /b document-1.txt + document-2.txt [+ additional fragments if the file divided into more than two parts] combinedfile.txt
  3. Save the combinedfile.txt as combinedfile.eml . Then open in Outlook Express and save the embedded attachment to your computer.

Split files can happen because most Lanier machines have a default scanned file size limit of < 10MB. This limit can be adjusted in the Lanier User Options.