These passwords, which you create on those companies’ account-management websites (like ), only allow syncing with those three kinds of services.

App-specific password expires: Many multi-service hosts, like Apple and Google, opted years ago to limit the risk of exposure of an account via calendar events, contact cards, and email message synchronization by creating app-specific passwords.

To resolve this, you will have to create a new password via the host’s website. (If you provided an alternate address for contact, they could send a message there.) Because you can’t know, it’s a good reason to check your mail host’s website or status page, as explained above. There’s no way for the company to reach you other than via email.

Host resets password: When there’s an attack against a service that manages accounts (mail or otherwise), they may take the prudent step to reset all passwords whether or not they know a successful breach occurred.

(I use Postbox and it provides a special pop-up web sheet in a window for this purpose.)

For one of my mail accounts, I have to refresh my email token weekly with a fresh login or access email is blocked. This occurs largely with corporate-style mail systems and web-hosted ones deployed by Google, Microsoft, and others for small and large businesses alike.

Token expires: You’re using a connection that creates a token stored in Mail, and the mail server causes that token record to expire.

However, there are some circumstances in which your legitimate email account and password need re-entry or a new password created: Your settings should never become corrupted: there’s no reason to re-enter details that were perfect the first time around.

An app-specific password may have expired or been revoked.

Mac incoming mail server