If enabled, when contact is added as guest on activity, a mail template will be sent with attached .ics file and activity information.
This option is useful if the contacts that are attending to the meeting does not need to receive an email containing the meeting information, for example, you are using an external software to handle such cases.
You can select a default activity type, the choosen type will be always pre-selected when creating a new activity, this option is based on your preference and in most cases, you should select the most used activity type in your company.
You can define activity types based on the activity you want to perform when creating activity, so you can have an overview of what the specific activity is related.
The activity types Call, Deadline, Email, Meeting, Task are the system default and cannot be deleted, as these types in future will be used over the system we don't recommend renaming them to some other name that has a different meaning.