What is a Signature Block? Guide to Email and Forum Signatures

A signature block (often abbreviated as sig block, sig file, or simply sig) is a personalized block of text that is automatically appended to the bottom of an email message, Usenet article, or forum post. It serves as a digital business card, providing the sender's identity and contact information.

Email and Usenet Signatures

An email signature is typically used to provide the sender's name, address, phone number, and other contact details. In the early days of the internet, "traditional" cultural practices favored monospaced ASCII text because they predated the use of HTML in email. This tradition often included brief author information, URLs, and sometimes a quotation or ASCII art.

Email Signature Generators

To simplify the creation of professional-looking signatures, email signature generators are available. These are apps or web apps that allow users to create designed signatures using pre-made templates without requiring HTML coding skills.

Signatures in Usenet Postings

Signature blocks are also widely used in the Usenet discussion system, where they follow specific conventions to help software recognize and separate the signature from the main message body.

Business Email Signatures

Businesses often mandate a specific style for their signature blocks to maintain brand consistency. These signatures often resemble standard business cards, including company logos and sometimes even a vCard attachment. Additionally, many companies append legal disclaimers to their emails to protect the company from liability, although the legal weight of these disclaimers is often debated.

Legal Requirements for Business Signatures

In several countries, certain information must be legally required in business-related emails:

• Germany: Requires disclosure of company name, registration number, and place of registration.
• Ireland: Requires limited companies operating websites to disclose similar information.
• UK: ECommerce Regulations require this information for all emails from limited companies.

The Standard Delimiter

The Usenet news system standards define a signature block as being delimited from the body of the message by a a single line consisting of exactly two hyphens, followed by a space, and then the end of line (-- ). This is known as the signature delimiter or sig-marker. This convention allows software to automatically mark or remove the signature block when a user is receiver is replying to a message, preventing redundant signatures from appearing in long email threads.

Internet Forums

On web forums, signature blocks are often more flexible. Users typically define their signature as part of their profile, and depending on the board's capabilities, they may range from a simple line of text to elaborate HTML pieces with images and dynamically updated information.