Today, I came across this error, that occurred when running an existing SSIS package:
Error: 0xC002F304 at Send Mail Task, Send Mail Task: An error occurred with the following error message: “Syntax error in parameters or arguments. The server response was: 5.5.4 Invalid Address”
After lengthy investigation, I discovered that one of the email addresses that it was trying to send to, had single quotes around it. Once I removed the quotes, the SSIS package ran through and completed successfully.