Within your Profile settings you can turn off the setting to receive UpMail's weekly report email that is sent every Monday.
To access your Profile, click on your email address in the top right corner and select 'My Profile'. From the main Profile page, scroll down to 'Other Settings' and turn the option to 'Subscrible to weekly reporting' off.
You will be able to reactivate the weekly reporting at any time by turning it on again.