openwith-mode opens attachments through message-send-and-exit

["Sven Bretfeld" <sven.bretfeld@gmx.ch>]

Hello all

This can't be a feature, can it?

When trying to send a message containing an attachment, the message will
not be send, but the attached file is "send" to an external program
instead while openwith-mode (or sex-mode) is active as a global minor
mode.

How can I switch off openwith-mode while writing a message? A mode-hook?
How can I secure that the mode is switched on again, after the message
is sent?

And more important, why is such a hook not part of these packages?

Thanks,

Sven