@bradhamilton Opera dropped ... Opera back many years ago, they released the mail client as a standalone program, and it was also possible to continue to use the last version Opera12.18
Vivaldi started a while after that, always with the promise that a mail client would be added, which is now available in the public builds since bit more than a year ago. The mail client is here to stay. And if Vivaldi stays alive as a company, which I sure hope it will, then they will keep the mail client as a unique feature.