eM >sometimes< sends multiple copies of the message.

There is no obvious logic in this problem; very embarrassing…Here is the log:

12:47:44 PM [Exchange Web Services]  Moving item(s) from folder ‘vlevenson@talevi.us/Inbox/’ to folder ‘vlevenson@talevi.us/Trash/’
12:48:03 PM vlevenson@talevi.us [Exchange Web Services]  MailClient.Accounts.ConnectionException: The underlying connection was closed: A connection that was expected to be kept alive was closed by the server. —> System.Net.WebException: The underlying connection was closed: A connection that was expected to be kept alive was closed by the server. —> System.IO.IOException: Unable to read data from the transport connection: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. —> System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
12:48:03 PM    at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult)
12:48:03 PM    at System.Net.Sockets.NetworkStream.EndRead(IAsyncResult asyncResult)
12:48:03 PM    — End of inner exception stack trace —
12:48:03 PM    at System.Net.Security._SslStream.EndRead(IAsyncResult asyncResult)
12:48:03 PM    at System.Net.TlsStream.EndRead(IAsyncResult asyncResult)
12:48:03 PM    at System.Net.PooledStream.EndRead(IAsyncResult asyncResult)
12:48:03 PM    at System.Net.Connection.ReadCallback(IAsyncResult asyncResult)
12:48:03 PM    — End of inner exception stack trace —
12:48:03 PM    at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status)
12:48:03 PM    — End of inner exception stack trace —
12:48:03 PM    at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute(WorkerStatus status)
12:48:03 PM    at MailClient.Commands.Command.Process(WorkerStatus status)
12:50:52 PM vlevenson@talevi.us [Exchange Web Services]  Moving item(s) from folder 

I think that when there is a connection problem like this, the server is not returning a confirmation that the message has been sent, and so it attempts to send it again.

You might want to open a support ticket so that the cause of the problem can be discovered and corrected.

Thanks, Gary! Do you mean support ticket with eM? I have the free version, so have access only to this forum…

Yes, eM Client Pro Support. If you are using the application for business use, you need to purchase a Pro License.