In OneOfficeERP, you can customize the Incoming and Outgoing Email Gateway. On saving an Email Account, OneOfficeERP tries establishing a connection with your email gateway. If your OneOfficeERP account is able to connect fine, then Email Account is saved successfully. If not, then you might receive an error as below.
This indicates that using login credentials and other email gateway details provided in the Email Account, OneOfficeERP is not able to connect to your email server. Please ensure that you have entered valid email credentials for your Email Gateway. Once you have configured Email Account successfully, you should be able to send and receive emails from your OneOfficeERP account fine.
Note: Your OneOfficeERP account is connected with an OneOfficeERP email server by default. If you don't want to use your own email server, you can continue sending emails using OneOfficeERP email server, without any configuration required in the Email Account.