Implications of removing session size limit from SMTP Virtual Server

Question

I am running into an issue in one of our applications whereby our SMTP server rejects mail:

System.Net.Mail.SmtpException: Exceeded storage allocation. The server response was: 4.3.1 Session size exceeds fixed maximum session size
   at System.Net.Mail.DataStopCommand.CheckResponse(SmtpStatusCode statusCode, String serverResponse)
   at System.Net.Mail.DataStopCommand.Send(SmtpConnection conn)
   at System.Net.Mail.SmtpConnection.OnClose(Object sender, EventArgs args)
   at System.Net.ClosableStream.Close()
   at System.Net.Mail.MailWriter.Close()
   at System.Net.Mail.SmtpClient.Send(MailMessage message)

I've traced this back to the session size limit in SMTP Virtual Server. It's currently set to 10240kb, but before I increase it I'd like to know the implications of raising the limit or removing it entirely. The only clients that send through the server are (should be) under the control of my organisation.

Answer 1

The implication is that more data will be allowed per session (connection), based on whatever you set the value to. So, in concert with the other limits, this determines how much total data (the sum of all messages sent per session) is allowed per session (connection).

Answer 2

To add to the previous answer, the SMTP service process will also potentially consume more memory if it allows to have more data sent in the same session. This is especially true if your SMTP server is setup to "store and forward" (receives and stores the message locally, sends a 200 code back to the sending SMTP server and then opens another connection to the destination SMTP server)