File and Folder Naming Rules

When mxHERO saves email and attachments to cloud storage, it cleans up every folder and file name so the provider accepts it. Names often come from email subjects and attachment names, which can contain characters that storage providers reject. This page lists exactly what mxHERO changes, so you can predict the names you'll see and design file paths that stay readable.

When these rules apply

They apply to every name mxHERO creates in storage:

• Each folder in a storage file path, including folders built from variables such as the subject or sender
• Each file name: saved emails (.eml, .msg), body PDFs, attachments, and ZIP files

The rules are applied to each folder name and file name separately, not to the whole path.

What mxHERO changes

mxHERO applies these steps in order:

1. Removes non-printable characters, emoji and pictographic symbols. Control characters and line breaks are removed. Symbols such as ✓ ★ ✂ and emoji are removed. Letters in any language (including Japanese, Chinese and accented letters), numbers, punctuation, currency signs, math signs and spaces are kept.

2. Removes these characters:

   :  \  /  *  ?  |  <  >  %  '  "

3. Removes #, except in Box and mxHERO Shares, where # is kept.

4. Shortens the name to 200 characters.

5. Removes trailing periods and tildes (. and ~) and trims spaces at both ends.

6. Uses EMPTY if nothing is left. For example, a subject made only of emoji becomes a folder named EMPTY.

Length

• Each folder name and each file name is cut to 200 characters.
• For files, the cut happens before the extension and any version suffix are added. A final file name can therefore be slightly longer than 200 characters, for example <200 characters>_v2.pdf.
• mxHERO doesn't limit the total path length. Your provider may: for example, OneDrive and SharePoint limit the full path length. Keep folder structures shallow and avoid long subjects in more than one folder level. See Microsoft's restrictions for OneDrive and SharePoint.

Note: Older mxHERO documentation described a configurable OneDrive path limit (400 or 1,000 characters) under Domains › One Drive Settings. That setting belonged to the retired dashboard and no longer exists.

Examples

Default file names

When a rule doesn't rename files, mxHERO uses these names (then applies the rules above):

If an incoming email already has an attachment named attachments.pdf, mxHERO renames it unverified-attachments.pdf, so recipients can tell it apart from mxHERO's own links file.

Duplicate names

• Within one email, attachments with the same name get a suffix: report.pdf, report_v1.pdf, report_v2.pdf.

• In a folder that already has the file, the rule's overwrite setting decides:

  Provider	Overwrite on (default)	Overwrite off
  Box	Saved as a new version (an identical file is left as is)	name_vN.ext
  OneDrive / SharePoint	Replaced	Renamed by Microsoft
  Google Drive	Saved as a new revision	name_vN.ext
  Egnyte	Saved as a new version	name_vN.ext
  Dropbox	Replaced	Renamed by Dropbox
  mxHERO Shares	Replaced	Replaced

Tips for clean names

• Use the Subject Normalized variable for folder and file names. It also removes reply and forward prefixes and replaces emoji with _. See Variables Reference.
• Use Attachment Normalized Name for attachment file names.
• Put dates in yyyyMMdd format at the start of names so files sort by date.
• Avoid using the full subject at more than one folder level.

Troubleshooting

Related pages

• Storage File Paths
• Variables Reference
• Storage Overview
• Supported Providers and Limits