Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host.

Frequently Asked Questions
1

Using version 7.2.34062.0

Use to work fine and one day … not able to send an email with attachment … work fine if no attachment

here’s the error

any clues?

4:38:22 PM [email protected] [SMTP]  Sending messages
4:38:22 PM [email protected] [SMTP]  MailClient.Accounts.SocketException: Sending messages failed due to the following reason:
4:38:22 PM     “Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host.”
4:38:22 PM    at MailClient.Protocols.Smtp.SmtpSendCommand.Execute(WorkerStatus status)
4:38:22 PM    at MailClient.Commands.Command.Process(WorkerStatus status)

No issues receiving emails … with attcahment

2

This is typically due to anti-virus software blocking the transmission.  Try disabling the AV software and see if you can send a message.  If yes, you will have to create a rule in the AV software that allows mailclient.exe through.

If this does not work, try the same with your firewall.