GET/install/apple-mail
Covered · file-swap

Install in Apple Mail.

Apple Mail on macOS doesn't accept a pasted signature — it stores signatures as files on disk. So you install by swapping the file's contents: make a placeholder signature in Mail, quit, and replace it with your Sigquill .htm. It's four steps and it holds perfectly once done.

Client
Apple Mail · macOS
Method
.htm file-swap
Time
~4 minutes
The method for Apple Mail
Download the .htm file.
.htm · required

In the builder, press Download .htm. You'll swap this file's contents into the signature Apple Mail creates on disk.

Copy & paste
Pasting into Apple Mail's signature box loses the layout — it stores signatures as files, so the file-swap is the only method that renders correctly here.

01Get your file ready

In the Sigquill builder, press Download .htm and note where it saves (usually Downloads). You'll open this file in a moment to copy its inner HTML into Apple Mail's signature file.

Your downloadsignature.htm
<!-- open this in a text editor to copy the inner HTML -->
<table role="presentation" cellpadding="0" cellspacing="0"> … </table>

02The file-swap steps

The trick: let Apple Mail create a signature file for you, then replace what's inside it. Follow these in order.

  1. Make a placeholder signature in Mail

    Open Mail → Settings → Signatures. Pick your account, click +, and type a couple of characters (anything — you'll overwrite it). This forces Mail to write a signature file to disk.

  2. Quit Mail completely

    Press ⌘ + Q. Mail must be fully closed, or it will overwrite your edit when it next saves.

  3. Open the signatures folder in Finder

    In Finder, press ⌘ + Shift + G and go to:

    Go to folder
    ~/Library/Mail/V10/MailData/Signatures

    The V10 part varies by macOS version (V9, V10, V11…). Open whichever V folder is present.

  4. Swap the contents into the newest .mailsignature file

    Find the most recently modified .mailsignature file — that's your placeholder. Open it in TextEdit. Keep the small header block at the top, delete everything below it, and paste in the inner HTML from your Sigquill .htm file. Save.

03Lock the file so Mail can't overwrite it

This is the one non-obvious step, and the reason most Apple Mail signatures revert. Before reopening Mail, lock the file you just edited so Mail keeps your version instead of rewriting it.

  1. Get Info on the file, then tick Locked

    Select the .mailsignature file, press ⌘ + I (or right-click → Get Info), and turn on the Locked checkbox at the top of the info panel. Now reopen Mail — your signature is available and won't be overwritten.

If your signature keeps reverting

That's the Locked checkbox not being set — Mail rewrote the file on its next save. Quit Mail, re-do your edit, tick Locked, then reopen. This single step is what makes it stick.

04Check it rendered

Compose a new message and pick your signature from the Signature dropdown. It should match the builder's proof panel exactly. Send one to yourself to confirm images load.

Don't see it in the dropdown?

Make sure you assigned the signature to the right account in Mail → Settings → Signatures, and that Mail was fully quit while you edited the file.

05Using Gmail instead?

Gmail is the opposite case: it renders real HTML, so you copy and paste — and you must never download the file there, because there's nowhere to install it. If you landed here by mistake, the Gmail guide is one click away.

Gmail: copy, never download

Downloading the .htm for Gmail is the single most common wrong turn. Gmail has no file-install path — follow the Gmail guide, which is copy-and-paste only.

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