Maybe this list is a start: https://en.wikipedia.org/wiki/Comparison_of_webmail_providers

But like another poster said, you don't have to put those 2 eggs (mailing and instant messaging) in the same basket:

• email and XMPP are distinct things
• you can absolutely have a mail provider AND a XMPP provider that are different entities
• that doesn't preclude using the same domain name for both services (this is a matter of DNS configuration and usages will be routed to the correct provider)

Essentially, what you need is:

• to register a domain with the registrar of your choice (and get a domain like matkalandar.tld)
• reach-out to a mail provider that lets you use your own domain name (google apps, mailbox, zoho, …) → they will service  your emails such as xyz@matkalandar.tld
• reach-out to a XMPP provider that lets you use your own domain name (conversations.im, snikket, …) → they will service  your chats such as xyz@matkalandar.tld

accounts, passwords, user accesses and management… will be different because effectively hosted by distinct service providers.