Errors with /outgoing/

I'm using the /outgoing/ feature, and getting a few (not all, or even a lot, just still several per day) File Does Not Exist errors. It's the inconsistency I don't understand.

The errors are formatted like this:
File does not exist: <path>/public_html/outgoing/http_www_SITENAME_com

Have you come across this before?

Hello,

please let me know an example URL where this happens.