End of support notice: On March 31, 2027, AWS will end support for Amazon WorkMail. After March 31, 2027, you will no longer be able to access the Amazon WorkMail console or Amazon WorkMail resources.
https://docs.aws.amazon.com/workmail/latest/adminguide/workmail-end-of-support.html
For alterantives:
Amazon WorkMail recommends customers migrate to third-party solutions such as Kopano Cloud, Zoho Mail, and Zoom Mail, each providing Amazon WorkMail-comparable capabilities and tooling for easy migration. You can also migrate to other in-market third-party solutions.
https://docs.aws.amazon.com/workmail/latest/adminguide/workmail-end-of-support.html
For alterantives: