How it works

What a cold email signature should carry

A name, a title, a company. That is the whole signature on a first touch. The recipient needs to know a person sent it and where that person works; everything past that is weight. A logo is a remote image load from a sender with no history. Four social icons are four more images and four more links. A tracked link gets rewritten through a tracking domain that carries its own reputation. None of these sends a message to spam by itself. Together, on an inbox that has been sending for three weeks, they are the pattern filters are trained on. The cold email type here outputs unstyled lines, keeps the domain as plain text unless you ask for a link, and tells you when you have crossed the budget. Run the result through the email signature checker if you want a second opinion on an existing one.

The opt-out line and the address

CAN-SPAM asks for two things a signature can carry: a clear way to stop the emails, and a valid physical postal address. The opt-out does not have to be an unsubscribe link. A sentence that says reply and I will stop is a legitimate mechanism, reads like a person wrote it, and adds no link. It also gives an annoyed recipient something easier than the spam button, which is the real reason to include it. The CAN-SPAM checker covers the rest of the copy, and the rules for the UK, EU and Canada.

What changes per platform

Gmail takes a rich-text paste, keeps inline styles and refuses anything over 10,000 characters, so the counter is measured against that. Classic Outlook edits signatures in Word: the photo is output square at a fixed size because Word will not crop or round it, and you can skip the editor entirely by dropping an .htm and .txt pair into the Signatures folder. New Outlook and Outlook on the web store the signature with the mailbox. Apple Mail needs one checkbox unticked or it re-fonts everything. Thunderbird wants the HTML itself, or a file. Microsoft 365 and Exchange Server sign on the server with a mail flow rule: the generator swaps your details for directory fields such as %%DisplayName%% and %%Title%% so one rule signs for the whole company, holds the output under the 5,000-character rule limit, and writes the New-TransportRule command with an exception that stops replies being signed twice. Instantly and Smartlead get plain HTML and spintax in each tool's own syntax.

Templates, and when an image signature is a bad idea

Classic, Modern, Panel, Monogram, Split, Stacked, Centred, Rule and Compact are all built from the same table markup, so switching template never changes what survives in Outlook. Monogram draws your initials in a coloured cell, which gives the signature a mark without hosting a file anywhere. The PNG and PDF downloads are there for places that are not email: a slide, a proposal, a letterhead, a LinkedIn banner. Do not paste the PNG in as your signature. An image-only signature has no clickable links, cannot be copied, is invisible to screen readers and to anyone with images off, and turns every email into a message that is mostly picture. The PDF keeps real text and working links; if the image host blocks cross-site reads, both exports are made without the photo and say so.

What survives Outlook

Classic Outlook on Windows renders HTML with Word, which ignores most modern CSS. The professional layouts are built the old way for that reason: nested tables, inline styles, pixel sizes, system typefaces, width and height set on the image itself. Round photo corners come out square there and nowhere else. Colours are mid-tones rather than pure black so dark mode inverts them into something readable; the dark preview approximates what Gmail and Outlook do, it does not reproduce any one client exactly. Images must be hosted files on https. Gmail strips embedded base64 images, and a link to a Google Drive or Dropbox share page is a web page, not an image, so it shows as a broken icon.

One signature per inbox

A cold operation runs dozens or hundreds of inboxes, each with a sender name that has to match its signature. Writing them by hand is where mismatches creep in: Marcus signing as Sarah on a rotated account. The bulk builder takes your inbox list, applies the type and options you set above to every row, and returns a CSV with the HTML and plain-text version per inbox. Instantly and Smartlead both hold a signature per account, in the account settings and through their APIs, and both place it with a tag in the sequence: {{accountSignature}} in Instantly, %signature% in Smartlead. A spintax closing word varies the sign-off per send; write it once in the account signature and the tool resolves it. The AI spintax generator does the same for the body.

Disclaimers

A confidentiality paragraph under an email has little legal force in most places, since a notice the recipient never agreed to binds nobody. Regulated firms add one because their compliance team requires it, and some countries require company details on business email: registered name, number and office in the UK, similar in Germany and much of the EU. If that applies, use the custom wording and keep it to the required facts. Two sentences is enough for everyone else, and none at all is fine for a cold email.

Versions for one platform

Same tool, one platform preselected, with notes written for it: Gmail signature generator, Outlook signature generator, Microsoft 365 company-wide signature and the cold email signature generator.

Frequently asked questions

Last reviewed September 17, 2026