Email Signature

An email signature is the block of text at the end of an email that identifies the sender, typically with name, role, company and contact details. In cold email it also builds credibility and can carry required legal details such as a postal address.

Cold Email & OutreachUpdated September 30, 2026

In short

An email signature is the sign-off block that tells the reader who you are and how to reach you.

Key points

  1. Signature blocks are a long-standing email convention inherited from letters and early Usenet posts [1].
  2. RFC 3676 describes the standard plain-text signature separator: two dashes and a space on their own line [2].
  3. Under the CAN-SPAM Act, commercial emails must include a valid physical postal address, which many senders place in the signature [3].
  4. Keep cold email signatures short and plain; large images and many links can look like bulk mail and hurt Email Deliverability.
  5. A consistent signature supports your Sender Persona and helps the reader verify you are a real person at a real company.

What to include

A good business signature answers who you are and how to check. The essentials are your full name, job title and company. A website link lets the reader confirm the company is real, and a phone number helps for prospects who prefer calls. Some senders add a professional profile link. The Wikipedia entry on signature blocks notes that early conventions favored a few lines only, and that advice still holds [1]. For cold outreach, resist the urge to add banners, badges, quotes or several social icons. Each extra element adds noise, and images in particular may be blocked or look promotional. Plain text renders reliably in every client.

Formatting conventions

In plain-text email, the signature traditionally starts with a line containing two dashes followed by a space. RFC 3676 documents this separator, and many email clients use it to detect and dim the signature or strip it from quoted replies [2]. HTML signatures are common in corporate mail but can break in replies and add weight to every message in a thread. If your company requires an HTML signature, keep it light: text, one small logo at most and no tracked links. Test how it renders on mobile, in dark mode and when quoted in a reply, since cold email threads often go back and forth several times.

Legal and trust considerations

The FTC's CAN-SPAM guidance requires every commercial email to include a valid physical postal address, which can be a street address, a registered post office box or a private mailbox registered with a commercial agency [3]. The signature or footer is the usual place for it, along with a clear Opt-Out line. In the EU and UK, company law in several countries also requires certain company details in business emails. Beyond compliance, the signature is a trust signal: a prospect deciding whether to reply will often check the sender. A real name, a real role and a working company website all make the Physical Address Requirement and the rest of your message more credible.

Sources
  1. Signature block — Wikipedia
  2. RFC 3676: The Text/Plain Format and DelSp Parameters — IETF
  3. CAN-SPAM Act: A Compliance Guide for Business — Federal Trade Commission
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Related terms

Physical Address Requirement

Put a real, current postal address in every commercial email; a registered PO box or private mailbox is acceptable in the US.

CAN-SPAM Act

CAN-SPAM lets you send commercial email in the US without prior consent, as long as you are honest about who you are, include an address, and honor opt-outs quickly.

Sender Persona

A sender persona is who your outreach appears to come from, and it should be a real, reachable person.

Plain-Text Email

A plain-text email is simple text with no design, which makes cold emails look personal.

Opt-Out

Every commercial email needs an easy way to say stop, and once someone does, you must stop emailing them within the legal deadline and keep them suppressed.

Email Deliverability

Deliverability measures whether your email actually lands in the inbox, not just whether the receiving server accepted it.

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