Pegasus Mail for Mac file
File type: Various data file
A pmdh file is a data file used by some versions of Pegasus Mail for Mac.
It belongs to the Macintosh edition of Pegasus Mail rather than being a general-purpose document.
File type category:
Various data file
Date updated: September 24, 2026
Pegasus Mail for Mac was the Macintosh version of the Pegasus Mail email program developed by David Harris. The pmdh file extension identifies a file used internally by some version of that software.
The exact role and contents of a pmdh file depend on the Pegasus Mail for Mac version that created it. It is part of the program's own data files and is not intended as a document format for other applications.
This is a legacy Macintosh format. The Windows version of Pegasus Mail should not be assumed to support pmdh files created by the Mac edition.
Open a pmdh file with the version of Pegasus Mail for Mac that created it, if that software is still available on a compatible Macintosh system.
The Windows version of Pegasus Mail is not a reliable way to open this Macintosh-specific file. Do not edit the file with a text editor, because it is an internal data file.
If the file can be accessed with the original Macintosh software, use that program's own export or migration facilities, where available, to move the relevant data to a supported mail format.
Software applications that handle other tasks involving pmdh files:
Microsoft Windows
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