In short: email marketing is much more effective and more convenient.

Telephone cold calling means: Constantly looking for new staff, training, salaries and / or commissions , the premises for a call center,  budget  for warnings, equipment … a lot of money, a lot of work, lots of stress.

Email marketing means: correct list can be found by the agency, creating a landing page, find a copywriters ,  create the art work – done.

I will illustrate with an example.