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What separates a signature that wins trust from one that gets ignored — twelve practical rules, no fluff.
The trust hierarchy your recipient scans first. Keep it to three lines max.
As tappable links, not plain text. Every extra contact channel dilutes the one you care about.
'Book a call' or 'View listings' — a single button outperforms a row of them every time.
A LinkedIn icon that leads to a dead profile hurts more than no icon.
License numbers and disclaimers styled small and grey — present, not shouting.
It dates you. Whitespace reads more professional than filler.
Arial, Helvetica, Georgia, Verdana — see our email-safe font guide. Custom webfonts silently fall back.
Wider signatures trigger horizontal scrolling on mobile, where most email is read.
Gmail and Outlook strip <style> blocks. Every rule must live on the element itself.
Attached images break. Hosted images with fixed width/height render predictably — details in our image size guide.
Outlook uses Word's rendering engine; what's perfect in Gmail can fall apart there.
Keep the whole signature under ~30KB so it never trips clipping or spam heuristics.
The rules flex by profession — a lawyer needs a confidentiality line, a realtor a license number, a photographer a portfolio link. Browse real examples, or generate one with every rule already applied.
Run your current signature against this before changing anything — most problems are removals, not additions.
Every additional line reduces attention on the ones people actually use. Cut the fax, the second mobile, the postal address and the quotation.
Many clients block remote images by default. If your name, role and phone live inside a picture, those recipients see nothing.
On mobile it should dial with one tap. This alone decides jobs in phone-first trades.
Two compete. Pick the one that matches how you get paid — see CTA examples.
It appears at every level of a reply chain. A tall block buries the conversation, especially on mobile.
Open it in Outlook, in Gmail and on a phone. A signature checked only in the editor has not been checked.
Several things people treat as design choices are really constraints imposed by email clients, and getting them wrong breaks the signature regardless of how it looks in your editor. Use inline styles, because Gmail strips style blocks. Use table-based layout, because Outlook for Windows renders through Word's engine and ignores modern CSS layout entirely — the full list is in the Outlook guide. Set explicit width and height on every image so nothing reflows while loading and Word cannot resize it. Use email-safe font stacks with real fallbacks, since web fonts are ignored (best fonts). And host your images over HTTPS with no login required (sizing guide). HTML email signatures explains why all of this is the way it is.
The skeleton above is universal; the required fields are not. Regulated trades have elements they must carry — a licence number for real-estate agents and electricians, NMLS IDs for mortgage brokers, compliance-approved disclosure language for financial advisors, and confidentiality notices for therapists and doctors. Requirements vary by jurisdiction and professional body, so confirm yours rather than copying another practitioner's block; the general framing is in legal requirements.
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Deeper on specific decisions: what makes a signature professional, what belongs in a signature versus your LinkedIn profile, and the HTML rules that decide whether any of it renders. For specific trades, healthcare, veterinary practices, notaries, architects, authors, musicians, travel agents, event planners, fitness trainers and property managers each have their own required fields.
ProSignature writes clean, tested HTML straight into Gmail via Google's API — free.
Create my signature — free3-6 lines. Name/role/company, one or two contact links, one CTA, and a legal line only if your industry requires it.
In client-facing and sales roles, yes — faces build trust. In corporate or legal settings a clean logo usually reads better.
HTML, built email-safe (inline styles, hosted images). Plain text is the fallback for mobile-app sends.
Doubly — consistency is the whole game. See email signatures for teams for central deployment.