HTML or image email signature: which to choose
There are two ways to build a "pretty" signature: design it as an image (JPG/PNG) and insert it, or build it in HTML with text and styles. The choice affects how — and whether — your recipients see it.
Image signatures: the problems
- Blocked by default: corporate Outlook and many clients do not auto-download images. Your recipient sees an empty rectangle with a broken-image icon. First impression ruined.
- Uncopyable data: your phone and email inside an image cannot be copied or clicked; the recipient has to retype them by hand.
- Invisible to inbox search: if someone searches for your phone number months later, they will not find it — it is a picture, not text.
- Ghost attachments: in reply chains, the image travels as an attachment ("image001.png") on every message, littering conversations.
- Accessibility: screen readers cannot read an image without alt text.
- Weight: multiplied by every email sent and replied to.
HTML signatures: the robust option
A text signature with HTML formatting (simple tables + inline styles) renders always, in any client, images blocked or not. Data is copyable, links are clickable, and the weight is negligible. Its only "limitation" is design: no exotic typefaces or complex compositions… which, in a signature, is a blessing in disguise.
The sensible middle path
If you want a logo, combine: HTML base (all data as text) + one small image (the logo, hosted on your server, with alt text). If the logo gets blocked, the signature still works 100%; if it renders, it adds brand. Never the other way around: never put contact data inside the image.
A modern detail: dark mode
More than half of emails are now read in dark mode. Keep in mind:
- Pure blacks in text invert well; dark grays can become unreadable. Use standard colors.
- A dark logo on a transparent background disappears in dark mode. Use a PNG with a white background or a logo version valid for both.
Conclusion
HTML with inline styles wins in every scenario that matters: deliverability, accessibility, search and weight. It is exactly the format our signature generator produces: pure text with a clean design that renders identically in Gmail, Outlook and Apple Mail.
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Frequently asked questions
Why does my image signature show up as an attachment on every email?
When embedding the image, many clients send it as an embedded attachment. In long threads, every message drags its own "image001.png". It is one of the main reasons to prefer HTML text signatures.
Can I use any font in an HTML signature?
Only the "safe" fonts installed on all systems: Arial, Helvetica, Verdana, Georgia, Times. Anything else gets substituted on the recipient's machine. Emails do not load web fonts reliably.
How do I make my logo look right in dark mode?
Use a PNG with a white (not transparent) background, or a logo version that works on both light and dark. Test by emailing yourself and toggling dark mode in Gmail and Outlook.
Can HTML signatures carry viruses or be dangerous?
A text-and-links HTML signature is harmless: mail clients do not execute JavaScript. An email's risk lives in its links and attachments, not in the signature's format.