Automatically Run macro

Hi All,

I have a cell in my Sheet which shows the last updated date ( E11), Now i
have macro coded which sents email from Macro if the difference last updated
date and todays date is more than 2, I have a cell E12 where I enter todays
date and my Email macro gets activated, my email macro is working fine

Only problem is that I have to enter the date on that cell manually for the
macro to execute, if i use today() function, it does not activate the macro
automatically.

Is there any way i can automate the email sending process if the difference
between E11 and E12 is more than 2.

i want the email to be send automatically once the dates changes in E12 at
midnight, I do not have to enter the date manually in E12.
PS: today() function in E12 not working

Any help?