Manage App Set Up Email Page Explained

On the "Manage Application" > "Setup" > "Email" page, you can set your general email settings.

Simpplr Emails
Select the "Enable Simpplr Email" box to turn on Simpplr Email. If this box is not checked, users will not receive any email.

Email Deep Linking
This setting is for mobile app. It means if you click on a link that generated by Simpplr, such as an email digest, the link will open Simpplr mobile app instead of a browser window.

Email Sender Address
You can select the "From" email address of your email notifications. This email address is pulled from the "Organization Wide Email" in Salesforce.

Newsletter
You can assign users who will be able to create newsletters. This set of users will see "Newsletter" when clicking on the avatar at the upper right hand corner. You should see a list of users you can choose from once you start typing a name.

Chatter Emails
You can select how you want to receive Chatter email. You can use your existing profile setting ("Existing profile assignment), turn it on for all users (On for all profiles), turn it off for all users (Off for all profiles), or turn it off for selected profiles. 

If you select "Off for selected profiles", you will see a list of profiles you need to choose to turn off email.