1&1 is now called IONOS, and the current IONOS Webmail lets you add an HTML signature under Settings > Mail > Signatures. If you're on the older 1&1 webmail, which didn't support HTML signatures, connect your account to a desktop or mobile email client and install your signature there instead.
Add your signature in IONOS Webmail
- Open your signature on htmlsig.com in Chrome or Firefox and click Open in New Tab.
- Select the whole signature in the new window and copy it (Ctrl + C on Windows, Cmd + C on Mac).
- Log in to IONOS Webmail, click the gear icon in the top-right corner, then click All settings.
- Click Mail, then scroll down to Signatures.
- Click Add new signature and give it a name.
- Click into the text field and paste your signature (Ctrl + V or Cmd + V).
- Choose where the signature should be inserted, then click Save.
- Click Set default signatures and pick your new signature for new messages and replies.
If your signature shows up as plain text, go to the Mail settings and make sure Allow HTML-formatted messages is turned on. If pasting loses the layout, use the editor's HTML or source code option and paste the code from the Source Code button on your signature page instead.
Use a different email client instead
If you're on an older webmail version that doesn't support HTML signatures, or you prefer a desktop app, add your IONOS (1&1) account to another email client using IMAP and install your signature there:
- Thunderbird
- Apple Mail on Mac
- Outlook for Windows and web
- Outlook for Mac
- Gmail (after connecting your IONOS account to Gmail)