Extend Mail autoconfig to check in server's autoconfiguration too
When a new mail account is setup in Thunderbird, the user enter her email address (local@domain) and then TB applies the procedure described at https://developer.mozilla.org/en-US/docs/Mozilla/Thunderbird/Autoconfiguration .
First it tries to call http://autoconfig.domain/mail/config-v1.1.xml?emailaddress=local@domain and then http://domain/.well-known/autoconfig/mail/config-v1.1.xml?emailaddress=local@domain. I suggest Evolution insists on calling https instead.
The idea is that the username does not have to be part of the email address and this cannot be solved by SRV lookups.
E.g. setup for firstname.lastname@example.org will call https://email@example.com and user for IMAP and SMTP will be "firstname.lastname@example.org".
Please intergrate this autoconfig system into Evolution.