Preventing failed email logins

To fend-off password-guessing attacks from hacker and spammers all our email servers are set up to temporarily block any IP address generating too many email login failures.

To prevent this from happening, the first step is to check that you have the correct password for your account, so start by going to https://webmail.his.com or http://webmail.domain.xxx and login using your email address as username, and your password.

Once you have verified that you have the correct password, gather all the computers and devices connecting from the current WIFI network.
On each one:

Edit the HIS-hosted email account setting and re-type the correct password

in the Incoming Mail settings
in the Outgoing SMTP server settings 

It may be easier to delete the email account from devices you don't use to check mail regularly any more (old phones, tablets. etc...) to prevent them from checking mail using an outdated password and generating errors.