Hi Dat Pham Kim,

Try to use rich text editor forge component - Ck editor 

https://www.outsystems.com/forge/component-overview/6885/ckeditor-reactive

You can go through the documentation and you can put the html content n image directly and it will show into the email.

You can check this post as well

https://www.outsystems.com/forums/discussion/26941/base64-image-in-email/

Hope this helps

Thanks

Prince

Ah I already have a html template, I example just like an image with parameters like:

<img src ="[{IMGSRC}]"/>

I want to replace the URL so that Gmail can load the image. I tested and found that CKEditor can upload the image and then get the URL. Is there any way to know the API they are using to upload an image, get the URL, replace the URL with the template then send an email?