When to setup multiple SMTP users
If you have many different senders using your SMTP2GO account, it is a good idea to give each of them a different SMTP username. We recommend that you do this if you have more than 10 different people send emails through your account.
This can be done on the 'Settings > Users' page in your SMTP2GO control panel.
The primary reason why creating multiple users is a good idea, is so you can easily prevent spam being sent through your account in the event of one of your usernames/passwords becoming compromised. If spam does get sent through your SMTP2GO account, you will be able to change the offending username/password, and advise the affected sender to immediately scan their computers for viruses/trojans.
Your other senders won't need to update their details.