SendMail input string not in the form for an e-mail address

Dim requestor As UserInfo = BRApi.Security.Authorization.GetUser(si, userName)
'Dim userEmail As String = requestor.User.Email

Dim emails As New List(Of String)

' Support mailbox
emails.Add("support@company.com")
emails.Add("user1@company.com")
emails.Add("user2@company.com")

' Requestor email
If Not String.IsNullOrWhiteSpace(userEmail) Then
    emails.Add(userEmail)
End If

' Optional: additional fixed recipients


BRApi.ErrorLog.LogMessage(si, "Email Recipients: " & String.Join(";", emails))

Dim mailThread As New Thread(Sub()
    Try
        BRApi.Utilities.SendMail(
            si,
            "OneStreamEmail",
            emails,
            emailSubject,
            mailBody.ToString(),
            True,
            Nothing
        )
		

Try with above