unable to log on. only one connection to a mailbox

How can I stop the password box from popping up with the message unable to log on. only one connection to a mailbox. There is nothing wrong because hours later you can click send receive and it loads messages. But why is this message coming up and how do I stop it? Thanks!

Hi Janine, can you make a screenshot of the issue?
Are you using any other devices to access your mailbox? From what you wrote I believe your mail service provider limits the number of connections to 1, which might be causing this error to popup if you have for example a smartphone setup with this email…

Thank you,
Paul.