We love to learn and improve hence our community members are always welcome to share any feedback related to Developer Nation by creating a post under this category.
About the colours used in the emails. You are using #18083a for the back ground which is close to html midnight blue and in your font for links you are using #6b27e8 which is close to html blueviolet.
The contrast is not great and in some light conditions the link text disappears. This also not great for people who are colour blind (Colour Vision Deficiency)