Yandex requires enabling IMAP in the settings before it can be used and supports enable visiturl:
$ curl https://autoconfig.yandex.ru/mail/config-v1.1.xml
...
<enable visiturl="https://mail.yandex.ru/neo2/#setup/client">
<instruction>Check IMAP setting on</instruction>
<instruction lang="ru">Включите настройку imap.yandex.com</instruction>
</enable>
...
Displaying this URL with description in some form can help users find the setting.