Definitely. Many of our customers do this and report that our mailer boxes hold up excellently in transit. They can be shipped all by themselves with no extra covering. Hooray!
In fact, a lot of customers use our mailer boxes for their 'subscription boxes'. These custom looking boxes help our customer's customers get excited about the inside of the box just by the awesome looking outside of the box. The mailers are often used to have a custom looking box filled with lots of different sized items, that when opened, display very beautifully.
Some gorgeous examples-
Standard White material mailer:
Kraft material mailer: