A task or calendar reminder email will appear on the Dashboard when you have set your account profile up so that any emails sent to your domain address from 'known contacts' are fed into your CRM email drop box address. 

In this case there will be a contact record already created called Support with the email address support@ recorded. 

Therefore any emails received from support@ such as task reminder or calendar event reminder emails will be recorded against the Support contact record. 

If you do not wish to see the task reminder emails on the Dashboard then follow the step below:

1. Simply remove the contact record called:  Support inside your CRM account.

2. Alternatively remove the email address so that in future any emails received do not automatically associate with this contact record.