As a Digital Marketing Agency, is outsourcing the services for our clients from another Digital Marketing Agency (called White Label Agency) permissible?

Concept of White Label Agency:

The term “white label” is a catchword in the realm of digital marketing. Basically, it means that an agency has a partner  that does work for them and their clients under their brand name. For example, my agency (referred to White Label Agency) offers SEO services to our agency partners, which they can then present to their clients as their own.
In a nutshell, a White Label Agency is a digital marketing agency that does the work for another digital marketing agency, and the original digital marketing agency which sought out the other gets the credit under its own brand name.