Assinatura de E-mail

How an HTML email signature is built

An email signature is the small block of identity that appears at the bottom of every message you send. A well-built HTML signature carries name, role, company, a small photo or logo, links (website, LinkedIn, Calendly), contact details (phone, email) and any required legal disclaimer. The layout is constrained the same way as any other piece of HTML mail: tables-based markup, inline CSS, no JavaScript (every client strips it), and ideally no external stylesheets. The target width is 320-480 px so it does not break on a phone preview, and the total file weight should stay under 100 KB including images to avoid the Gmail "[Message clipped]" warning at 102 KB.

A skeleton signature looks like this — two columns (image + content), Arial fallback so Outlook does not substitute a serif, and explicit colours so dark-mode auto-invert behaves:

<table cellpadding="0" cellspacing="0" style="font-family: Arial, sans-serif;">
  <tr>
    <td style="padding-right: 12px;"><img src="https://cdn.example.com/photo.jpg" width="64" height="64" alt="Jane"></td>
    <td style="font-size: 13px; color: #111;">
      <strong>Jane Doe</strong><br>Product Designer · ACME<br>
      <a href="mailto:[email protected]" style="color: #1e40af;">[email protected]</a>
    </td>
  </tr>
</table>

Images, vCard and brand consistency

Logos and photos must be hosted on a public CDN — embedding base64 inflates the message and many filters reject it. Always set explicit width, height and alt attributes so the layout stays stable when images are blocked. For brand consistency stick to web-safe fonts (Arial, Verdana, Georgia, Tahoma) — Outlook substitutes Google Fonts with Times New Roman silently. A nice touch is a vCard download link (.vcf file) so recipients can save the contact in one click on iPhone or Outlook.

Mobile, legal and GDPR/LGPD considerations

More than 60% of business email is opened on mobile, so social icons should be sized 32-44 px for tap-friendliness and the whole block should not exceed 480 px wide. Regulated industries (legal, finance, healthcare) typically require a confidentiality notice — keep it short and visually de-emphasised (smaller font, lighter colour) so it does not steal attention from the brand block. In Europe GDPR considers the signature a controller identification point; in Brazil LGPD does not mandate disclaimers but companies often add a privacy-policy link.

Generators, Outlook quirks and A/B testing

Specialised generators include WiseStamp, NEWoldStamp, HubSpot Email Signature Generator, Mailmodo and MySignature. Microsoft Outlook stores signatures as a trio of files — .htm + .rtf + .txt — in %APPDATA%\Microsoft\Signatures; replacing only the .htm file does not update the RTF fallback. Gmail's signature editor strips background colours and complex CSS, so test the final HTML inside the actual web Gmail composer. Like any marketing asset, signatures are worth A/B testing — measure click-through on the portfolio or Calendly link with UTM tags.

FAQ

Can I embed a video in my signature? No client supports inline video playback in email. The standard pattern is an animated GIF thumbnail with a play-button overlay, linking to YouTube/Vimeo — but keep the GIF under 1 MB or it slows down the inbox.

What is the file-size limit? Keep the whole signature under 100 KB. Gmail clips messages larger than 102 KB and hides the rest behind a "[View entire message]" link, which kills your CTA visibility.

How do I handle multilingual teams? Either prepare one signature per language or use a single English signature as the universal fallback. Some teams set up automation rules (Outlook server-side, Google Workspace add-on) to swap signatures based on recipient domain.

Common mistakes to avoid? Too many emojis (looks unprofessional), text below 12 px (unreadable on mobile), embedded video (rejected), heavy animated GIFs (slow inbox), broken links to a personal Facebook (off-brand), and missing alt text on images (signature collapses when images blocked).