npub1rv0xtc5q9n9ss7hyc4tand6myhyq6sp7r49ucfnywkhyfxpjhaes2wxuyz (npub1rv0…xuyz) Hi! It doesn't have to be Gmail. As long as you import emails, contacts and calendars from an external service using our EasySwitch (https://proton.me/easyswitch), you check that one off the list. If there's an issue, make sure to contact us at: https://proton.me/support/contact.
Gmail is given as an example, because, in addition to the import, EasySwitch allows you to set up automatic forwarding from Gmail, without sharing your Proton Mail address with Gmail.