Outlook/Exchange message subheader
application/octet-stream
Magic Bytes
Offset: 0
D0 CF 11 E0 A1 B1 1A E1
The Outlook Item File format is a proprietary standard developed by Microsoft for storing individual email messages, appointments, contacts, and tasks. It is primarily utilized within the Microsoft Outlook and Exchange ecosystem to archive communications or transfer specific items between users while preserving original formatting and metadata. Built upon the legacy OLE Compound File Binary architecture, this container encapsulates message properties and attachments within a complex structured hierarchy.
Validation Code
How to validate .msg files in Python
Python
def is_msg(file_path: str) -> bool:
"""Check if file is a valid MSG by magic bytes."""
signature = bytes([0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1])
with open(file_path, "rb") as f:
return f.read(8) == signatureHow to validate .msg files in Node.js
Node.js
function isMSG(buffer: Buffer): boolean {
const signature = Buffer.from([0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1]);
return buffer.subarray(0, 8).equals(signature);
}
Go
func IsMSG(data []byte) bool {
signature := []byte{0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1}
if len(data) < 8 {
return false
}
return bytes.Equal(data[:8], signature)
}API Endpoint
GET
/api/v1/msg
curl https://filesignature.org/api/v1/msg