This issue is due to increased security on many email platforms. The solution to this error is to allow less secure apps in your email account information or to use app specific passwords, depending on which email provider you use.

For example:

With Yahoo! Mail –

• You must log-in and then navigate to your “Account Information”.
• From here go to “Account Security”.
• Find the “Generate App Password” option on this page and follow the prompts.
• This password will be used in EBPro in place of your account password under the Email tab in System Parameters.