MSF File Extension

Application Associated Mozilla corporation
Category email related data
Supported Platforms Windows, Mac, and Linux

What is .msf File?

MSF file extension belongs to mail summary file. It is a mailbox folder index that can directly open in a text editor but is not human readable. Each Thunderbird mail folder like Inbox, Sent, Drafts, etc is stored as two files: one without extension (for e.g. Sent), which is the Thunderbird mail file itself and the other with an .msf extension (for e.g. sent.msf), which is the Mail Summary File to the mail file. If the .msf file is damaged, Mozilla Thunderbird will display problems to accessing the affected Thunderbird mailbox folder. These files only contain an index of the message and mail headers and summaries.

MSF File Location

These file can be stored in the following locations

  • Windows Vista: C:\users\Users Name\AppData\Roaming\Thunderbird\Profiles
  • Windows 95/98/ME: C:\Windows\Application Data\MozillaThunderbird\Profiles\xxxxxxxx.default
  • Windows XP/ Windows Server 2003C:\Windows\Application Data\Mozilla Thunderbird\Profiles\xxxxx.default

Identifying Signatures

Hexadecimal: 2F 2F 20 3C 21 2D 2D 20 3C 6D 64 62 3A 6D 6F 72 6B 3A.