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 > SMTP 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.
For further separation, accounts on paid plans can split sending out to different Subaccounts. Further information on Subaccounts can be found here.