指定的格式不是电子邮件地址所需的格式

Question

@Exception：SystemFormatException：指定的格式不是电子邮件地址所需的格式

这是发生错误的代码，请帮忙。

Public Sub send_email(ByVal code)`
    Dim tsURL As String = "http://string/server/"
    Dim n As Integer
    Dim email_add As String
    conn1("SELECT * FROM hr_employee WHERE emp_position IN ('QA ENGINEER', 'SR. QA ENGINEER') AND status = 'employed'", "email_add")
    If ds.Tables("email_add").Rows.Count > 0 Then
        For n = 0 To ds.Tables("email_add").Rows.Count - 1
            dr = ds.Tables("email_add").Rows(n)
            If n <> ds.Tables("email_add").Rows.Count - 1 Then
                email_add = email_add + dr("email")
                email_add = email_add + ", "
            Else
                email_add = email_add + dr("email")
            End If
        Next
    End If   

 Dim MailFrom1 As String = "e@mail.com"
 Dim MailTo1 As String = email_add
 Dim MailSubject1 As String = "New Carrier Tape : " & code
 Dim MailBody1 As String = vbCrLf & "A new carrier tape (Part Number: " & code & ") has been added into the system. Please verify and buy-off the specs in the MRP system. " & vbCrLf & vbCrLf & "MRP System: " & tsURL & vbCrLf & "Module: Manufacturing --> First Article --> QA"
Dim MailClient1 = New SmtpClient("localhost")
MailClient1.send(MailFrom1, MailTo1, MailSubject1, MailBody1)
'Catch ex As Exception
'End Try