Sending Email Error


I was wondering whether someone could give me a suggestion of what the below error means when sending an invoice by email?

System.FormatException: System.FormatException: Smtp server returned an invalid response.
** at System.Net.Mail.SmtpReplyReaderFactory.ProcessRead(Byte buffer, Int32 offset, Int32 read, Boolean readLine)**
** at System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine)**
** at System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller)**
** at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)**
** at System.Net.Mail.SmtpClient.GetConnection()**
** at System.Net.Mail.SmtpClient.Send(MailMessage message)**

I have recently changed my email settings to the following:

I have spoken with support where my email is hosted and they are unable to find any problems that would stop emails sending from Manager at their end.

I have tried selecting use SSL, unchecking SMTP server requires authentication without success and combination of the two.

Any advice or suggestions would be much appreciated.



Have you tried the exact same credentials in an email client such as Thunderbird? It’s more likely to report
in a more human friendly waywhat went wrong in with establishing a connection with the server.

You are using port 587, in that case you must check Use SSL option.