To insert the date automatically, you can use one of the following Addemar tags:

<?add_date_day?> : this is the day of sending.
<?add_date_month?> : this is the month of sending.
<?add_date_year?> : this is the year of sending.

So for example, if you want to add the day-month-year into your email campaign, you'll need to use the following format

<?add_date_day?>/<?add_date_month?>/<?add_date_year?>

Here the example in a email creation.

These tags will be replaced once the mail is sent out and will calculate the correct specified date.

This will give the following result.