You need to use Browser action "Open URL" or "Go to URL" with the following link:
mailto:abc@gmail.com?subject=Bugreport&body=message
Use URLEncode() expression to encode the subject and body message if needed.
Note, that this will not automatically send the email. It will only open an email app on user's device and compose the email for sending.
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Another option is to use an online service like sendgrid.com (the first one I found in google).