Android devices are known for poor HTML signature support in most email apps.
No official Gmail, Outlook, or Yahoo apps can let you install HTML signatures. However, here are three workarounds that may work for you:
First, you can use Gmail or Outlook web apps.
You can use Gmail and Outlook in your browser by going to gmail.com or outlook.com, respectively. It grabs your signature from the account where you had your signature installed (installed it on Outlook Web Application or Gmail prior).
If you need to send an email with an HTML signature in Gmail, please open the Chrome browser and log in to your Gmail there. It's mail.google.com. You can go to the settings and check if the Mobile signature is turned off.
The signature won't be visible while composing a message, but whenever you send an email from Gmail in Chrome, it grabs your signature from the desktop Gmail account.
The same works with Outlook.com. If you have installed the signature in Outlook on the Web, you can just select Use my signature from Outlook on the Web in the signature settings in your browser.
2. Create and use a plain text signature in your Gmail app. We'd like you to follow our detailed guide on How to install the signature in the Gmail app on an Android phone.
3. Use Samsung Mail (for Samsung Galaxy s8+ and newer).
If you are holding a Samsung Galaxy s8+, s9, or any newer version that came out, you can use your default Samsung Mail app that would let you install an HTML signature in the Email Signature Settings of your app by copying it and pasting it there.
4. Use third-party apps and sync your email with them.
There are a few apps on the market that can handle HTML signatures. Currently, we have discovered Spark, Nine, Aquamail, and Newton.