I have an SSIS project working in VS2015 set to SQL-Server 2012. I send a success or failure e-mail at the end of package execution using an EMailAddressList project parameter. The Send Mail task editor has an expression of @[$Project::EMailAddressList] for the ToLine field. This works great if the EMailAddressList project parameter only has one e-mail address in the like JohnDoe@MyCompany.com. But if I try to add a second e-mail address to this parameter using either JohnDoe@MyCompany.com; JaneDoe@MyCompany.com or JohnDoe@MyCompany.com, JaneDoe@MyCompany.com, the Send Mail task shows the error message: Validation warning. Send Success Mail Send Mail Task: The address in the "To" line is malformed. It is either missing the "@" symbol or is not valid. What is wrong and how do I fix this?
After a bit more Google, I found the answer. There is nothing wrong with the way I am doing it, it is just failing Validation. When I set DelayValidation to True for my Send Mail task, I no longer get the message and the package executes without errors. All recipients received the successful execution e-mail.