forwarded messages remain in outbox, cannot send, please help?

If I forward a message, with an attachment, It does not send.
The message remains in the outbox.
The original message disappears from my inbox and stays attached to the unsent message, as a conversation.
If I give up, and delete the unsent message, then I lose the original message too. 
I just cannot figure out what setting I have wrong!
Please, any suggestions will help, Thanks

Forwarded emails should never disappear from your inbox unless they are manually deleted.

Sounds like something is intercepting or delaying your outbox mail & attachments. Strange why your inbox emails are disappearing.

Do you use any optional eg: antivirus / security / firewall filtering program of any sort ? Also what version of EM Client are you using and are you using Windows or Macintosh.