What must be the image size which I use in custom mail template

What must be the image size which I use in custom mail template

Hello Support,

I am brand new user of Zoho campains and I am still adjusting the mail template for my first campaign. The very first problem which I came to is the image size. I have created a custom responsive mail template with html which I uploaded in Zoho campains. I have uploaded one logo and 4 images separately, as you have stated. I have sent the campaign to several mail addresses just for test and I have a problem with the size of pictures in some mail clients viewing through mobile phones. See attached file. I can not see the whole mail template, I am able to see just part of it, which is very strange because the width of this newsletter is only 600px.

The second problem which I have faced that in Microsoft outlook 2007 I am not able to see some elements like backgrounds of buttons. See attached screenshot. Can you give me some advice what to do?

Best regards,
Nadejda