Why are the corners of my email layout not rounded like it is in the preview?

[Simran9]

In the email notification layout, this square in the middle of my image has rounded corners:

But in outlook the corners are square:

Why is it doing this and how can I fix it?

[Slava Savitsky]

Not all CSS properties are supported by all email clients in the same way. Therefore, your email notification may look slightly different depending on what email client it is being viewed in.