If I am an email marketer why would I want my emails to be auto-deleted at all? Even if you added some new legislation requiring me to add an expiry time to em

If I am an email marketer why would I want my emails to be auto-deleted at all? Even if you added some new legislation requiring me to add an expiry time to email messages the standard practice would be to make this as long as possible and to simply send new emails out the minute that the old ones expired.