Compatibility

This is the universal install flow. It works with any email client that lets you paste HTML or rich text into the signature editor — which is most modern desktop and web clients. We confirmed it works with Thunderbird, Spark, Mailbird, Em Client, Proton Mail Web, FastMail, and Zoho Mail. It will also work with most other clients we haven’t formally tested. Mobile clients vary — see “Mobile clients” below.

Before you start

• Identify whether your client supports HTML signatures or only plain text. Most modern clients support HTML; some specialized or legacy clients are plain-text-only.
• Have your Sigent.ai install link ready (from the Share button in your dashboard).
• Know where the signature settings live in your client. Usually under Settings → Mail → Signature or Compose preferences.

Steps

1. Open your Sigent install link in any browser.
2. Click Copy to clipboard. The HTML is now in your clipboard.
3. Open your email client and navigate to the signature settings.
4. Create a new signature or select an existing one to overwrite.
5. Click into the signature editor and paste with Cmd/Ctrl + V. Some clients offer “Paste as HTML” or “Keep formatting” — choose those if available.
6. Set the signature as default for new messages and replies if your client supports that.
7. Save and close settings. Compose a test email to confirm.

Verify your signature

Send a test to yourself (or to a Gmail address you control). Open it both in your client and in Gmail Web. If the styling matches in both, your client supports the signature fully. If your client strips formatting, see Troubleshooting below.

Troubleshooting

• My client only shows plain text after pasting. Look for a rich-text or HTML toggle in the signature editor. Some clients (Thunderbird before 91, older Em Client) default to plain text and need an explicit switch. If no toggle exists, your client may be plain-text only — in that case, copy the plain-text version Sigent provides alongside the HTML and use that.
• Formatting drifted after paste. Try Edit → Paste Special → Keep Source Formatting or Paste as HTML, depending on the client. Some clients re-process pasted HTML through their own sanitizer, which can strip styles.
• Images don’t appear. This is usually a CORS or image-loading policy in your client. Make sure the recipient can load images from cdn.sigent.ai (or your custom CDN if configured). Some privacy-focused clients (Proton Mail) block external images by default — recipients need to click “Load remote content.”
• Links don’t open as clickable. Your client may have rendered the signature as plain text rather than HTML. Re-check the paste method (see first item above). Confirm in your client’s compose window that the signature appears with active hyperlinks.
• The signature works on desktop but not on mobile. Most mobile clients have their own signature settings, separate from desktop. Repeat this install flow in the mobile app, or accept that mobile shows a simpler plain-text signature.

Mobile clients

Mobile clients that support HTML signatures: Outlook for iOS/Android (limited), Apple Mail iOS (via iCloud sync from macOS), Spark for iOS/Android, and Proton Mail mobile.

Mobile clients that strip to plain text: Gmail for iOS/Android (uses a server-side signature), most native Android Mail apps from manufacturers (Samsung, Huawei, etc.).

If your mobile client strips formatting, consider using a plain-text signature on mobile and the full HTML signature on desktop. Sigent’s render engine emits both versions side-by-side.

Need help? Contact support — we usually respond within 24 hours.