Email Security with SendGrid - what are the risks?

[Runecaster]

DeaD_EyE and nilamo, Thank you very much. From both your answers, my understanding is that not storing the key in a secure file is the issue. The emails being sent out themselves cannot be tampered with by anyone outside (generally speaking). And as long as the API Key is stored in a secure location where it cannot be accessed without permission, I should be reasonably safe in sending these emails.

Thanks again for your help!