Email signature generator › Font changes

Why the font in your signature changes

You chose a typeface, the recipient sees a different one. This is not a bug in your signature: email has no reliable way to deliver a font, and understanding what happens instead tells you what to choose.

There is no font delivery in email

On the web, a page can tell the browser to download a typeface. In email that mechanism is unavailable in most clients: web font declarations are stripped by Gmail and ignored by Outlook for Windows entirely. What actually happens is that the recipient's client picks from the fonts already installed on their machine, working down the list you provided.

So a signature set in a font your recipient does not have will render in something else, chosen by their client, and there is nothing wrong with your markup when that happens.

The fallback stack is the real setting

Because the client works down a list, what you write matters: font-family: Georgia, 'Times New Roman', serif means "Georgia if you have it, otherwise Times New Roman, otherwise whatever your serif is". The last entry should always be a generic family — serif, sans-serif — so that even an unusual system lands somewhere sensible rather than on the client's default, which is often Times.

A single font name with no fallbacks is the most common mistake. It means every machine without that font falls all the way through to the client default, and the result is much further from your intent than a chosen fallback would be.

Which fonts are actually safe

The set present on effectively every Windows and macOS machine is small: Arial, Helvetica, Georgia, Times New Roman, Courier New, Verdana, Tahoma, Trebuchet MS. Anything outside that will work for some recipients and not others, which is acceptable for a decorative element and not for the block that carries your phone number.

Note that Helvetica and Arial are close enough that Arial, Helvetica, sans-serif gives a nearly identical result on both platforms, which is why that stack is so common.

Outlook and the Word default

Outlook for Windows has a further habit: where it cannot resolve a font declaration it falls back to the Word default rather than the browser default, which historically means Times New Roman. A signature that looks modern in every other client can arrive in a serif face in Outlook for no visible reason. Naming a generic sans-serif at the end of the stack prevents it.

Set the font on every cell

Font declarations do not inherit reliably through email HTML the way they do in a browser. Setting font-family once on a wrapper and expecting the cells inside to pick it up works in some clients and not others. Put the declaration on each table cell that contains text. It is repetitive and it is the only approach that behaves the same everywhere.

Font size behaves differently from font family

Size is honoured much more consistently than family, with one exception that catches everyone: phones scale text they consider too small. Below roughly 13 pixels, iOS and several Android clients enlarge the text on their own, which changes where your lines break and can push a two-column signature out of shape.

Setting the signature at 14 pixels avoids the scaling entirely and is legible on every device. It looks a shade larger than a designer would choose on a desktop, and that is the right trade for a block whose job is to be read rather than admired.

The bold and italic trap

Using <b> and <i> is safe. Using font-weight:600 is not: many of the fonts available on a recipient's machine have only regular and bold, so a semi-bold declaration resolves to one or the other unpredictably, and the same signature can look noticeably different on two machines. Use 400 and 700 and nothing in between.

Checking what the recipient's client chose

If you want to know which font actually rendered rather than guessing, open the received message in a desktop browser through webmail and inspect the element. The computed style shows the font that was resolved from your stack. It is the only way to distinguish "my font was ignored" from "my font was never in the stack in the first place", and the second happens more often than people expect after a signature has been pasted through two editors.

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