It can be pretty frustrating to not be able to set up your email account anywhere, be it Outlook, Mailwasher or anywhere else. The first thing to do is to obviously look to make sure you have the correct password. Some users have complained that they faced this issue after they changed their BT ID and password for some reason or other. Then they start to wonder what they are doing wrong, if they are missing out on a password change lag time that may exist, or some cache that needs to be cleared.
To get rid of this issue, you should first switch all of your devices off. If not that, then you absolutely have to not allow them to poll your email account for a new email. This can be done by changing the mail address in the account settings for the email or deleting the email account completely from the devices in question. Now, go ahead and change the password for your email on the web and give it fifteen to thirty minutes before turning on the devices and try setting up the email account on them with the new password that you changed.
Make sure that the first device is working well before you move on to the second device. Also, make sure that your mail is set on the correct settings and set up the account manually instead of allowing the email wizard to do it.