When users try to reset their password via the MimeCast portal, the user gets to the "received your verification code" step and then they get the following error:
Sorry, something went wrong. please try again later, if the problem persists, contact your system administrator.
This error is almost always caused by Password Resets being disabled from Application Settings. In your case, this is also true.
You will want to navigate to Services > Services > Applications and click Authentication Profiles. Choose the Default profile that is in there and change the option next to ‘Password Reset Options’.