What is SIG? What Opens a SIG? File Format List from WhatIs.com

File Extension

SIG File Format

Signature file (PopMail)

SIG is a signature file format used in POPMail. SIG files are usually placed at the end of an email, and usually contain information such as a business name and contact information. POP stands for Post Office Protocol, and is currently in its third version (POP3). POP3 is used by most e-mail servers, such as Gmail and Outlook Express.


Learn more about .SIG files:

Learn how to create ad-aware signature files for Microsoft Outlook.

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This was last updated in July 2010
Editorial Director Margaret Rouse

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