Question

When clicking an email address from a browser or contacts app…

Is there any way for my app to show a mail client in the intent list?

Answer 1

As you can see from the Mail application’s source, having your application catch the intent is as simple as adding the intent-filter to your AndroidManifest.xml inside your mail composition activity definition.

<intent-filter>
    <action android:name="android.intent.action.VIEW" />
    <action android:name="android.intent.action.SENDTO" />
    <data android:scheme="mailto" />
    <category android:name="android.intent.category.DEFAULT" />
    <category android:name="android.intent.category.BROWSABLE" />
</intent-filter>

You can see that the <data> tag specifies to handle mailto: links. The BROWSABLE category means it can be launched from the browser.

K-9 Mail is similar, except using the SENDTO action only with the DEFAULT category, and the VIEW action only with the BROWSABLE category.