Try the marketplace module: https://marketplace.mendix.com/link/component/118937/Salij/SendGrid-Email
I have not implemented send grid, but you can achieve using the rest services since send grid has API to send emails. you can follow this link for reference:
https://docs.sendgrid.com/for-developers/sending-email/api-getting-started and also with Mendix module Send grid
But out of curiosity, why are you opting for send Grid, you can make use of the Mendix email Template module which is easy to integrate and quick set up of templates and Configuration.
Here is the link for the module, if you have other thoughts of implementing this :)
Hope it helps. All the best!!