Signature Studio

Outlook desktop — Windows

1. Press Copy signature above.
2. In Outlook: File → Options → Mail → Signatures… (or hold Ctrl while clicking Signature on a new message).
3. New, give it a name, and OK.
4. Click inside the large edit box and paste with Ctrl+V. Paste plainly: Ctrl+Shift+V strips the formatting and leaves you bare text.
5. On the right, set New messages and Replies/forwards to the signature you just made.
6. OK, then send yourself one message to check it.

The logo is pulled from this site the moment you paste. Outlook saves its own copy into your Signatures folder there and then, and attaches it to each message you send — so it keeps working for the people who receive it, and it survives this site going away.

Outlook desktop — macOS

1. Press Copy signature.
2. Outlook → Settings → Signatures, then +.
3. Paste into the editing pane with ⌘V.
4. Close the editor, then pick the signature under Choose default signature for your account.

If the paste comes out wrong

1. Everything is plain text — you pasted with Ctrl+Shift+V, or the clipboard lost the HTML. Press Copy signature again and use plain Ctrl+V.
2. No logo, just a box — Outlook could not reach the image. Open the logo URL in a browser to check it is public, then paste again.
3. Nothing pastes at all — some managed installs lock the clipboard down. Press Download .htm, then in Windows open Win+R → %APPDATA%\Microsoft\Signatures and drop the file in.
4. Extra blank line above the signature — that is Outlook, not the block. Press Shift+Enter instead of Enter when you type above it.

Elsewhere

1. Outlook on the web — Settings → Mail → Compose and reply → Email signature, click in the box and paste.
2. Gmail — Settings → See all settings → Signature → Create new, then paste. Gmail rehosts the logo on its own servers.
3. Apple Mail — Mail → Settings → Signatures, and untick Always match my default message font before pasting.