If I change email in preferences then I get no mail at the new address but two at the old.
One is a warning that somebody has changed the email address. This is OK.
The other is the mail with the confirmation link which should have been sent to the new address.
When the link is clicked the old address and not the new is stored in preferences.
The only way the new address can be accepted is apparently to ignore the first confirmation mail and instead request a new. The new one is sent to the new address and the confirmation link stores the new address.
The new address is one that has always worked with Wikipedia mail.
Two other users had the same problem and solution at