SMTP Error Code
Server says: 530 5.7.0 Must issue a STARTTLS command first
Solution: Server says: 530 5.7.0 Must issue a STARTTLS command first.
In GroupMail, Modify your Sender Account in the Account Manager.
Under the Delivery Options Tab, Advanced Button.
Enable the Option “Server requires an SSL Connection”
Select STARTTLS (default) from the drop down list.
Press Ok, Ok to Save these changes.
As always, feel free to contact the GroupMail support team if you need any further information.