Biztalk FILE Send Port throws "The system cannot find the file specified"

If you receive this exception in BizTalk

A message sent to adapter "FILE" on send port "SENDPORT_FILE" with URI "\\ABC\PATH\%MessageID%.xml" is suspended. 
Error details: The system cannot find the file specified. (Exception from HRESULT: 0x80070002)
MessageId:  {5EC92559-C6E3-490C-A1D4-981D154BA126}
InstanceID: {4FF0F3DE-9A4C-4ECE-8C5A-98B34C78701E}

the reason could be that BizTalk does not find the assembly during runtime in the GAC, although it was there. In my case, I had to create the assembly in Development mode instead of instead of and then BizTalk could find the assembly.

Setting the mail address of Receiver in the Pipeline Component

If you want to send a message with a static or dynamic SMTP send port, you can configure the mail address of the receiver in a pipeline component. Therefore, you have to promote OutboundTransportLocation in the message context of the message:

msgContext.Promote("OutboundTransportLocation", "http://schemas.microsoft.com/BizTalk/2003/system-properties", "mailto:" + mailAddress);