Answer:
Yahoo! mail
Step-by-step explanation:
In the context, Dona travels most often around the world. While traveling, she has to access her emails from different location and at different times. But in order to keep her luggage light, she never carries the laptop with her. Therefore, Donna uses Yahoo! mail to access her emails.
Donna uses Yahoo mail because she can install the Yahoo! mail app in her phone or tablets which is small in size and of light weight. She is able to organize her Outlooks, Google mails and Yahoo accounts. In Yahoo! mail, Donna is also able to sign in with her any of the non yahoo accounts and it also provides free cloud storage space.