Help please

[Alfredo Hassaf]

Can any body tell me why sometimes when I send a message with attachments,
it comes back to me with this error:

Your message did not reach some or all of the intended recipients.

      Subject:  Emergencia !!!
      Sent:     24/11/00 1:14 PM

The following recipient(s) could not be reached:

      '[EMAIL PROTECTED]' on 24/11/00 1:23 PM
            No transport provider was available for delivery to this
recipient.

Any help?????

Jos� Alfredo Hassaf Abraham
Quitze S.A. de C.V.
5545-1286 y 5545-1287