Your problem isn't with Windows Mail.
Any other mail client program would produce the same result.
Evidently, the destination mail server of one of your recipients does not like
the anti-spam profile of the originating mail server.
The only workaround is to use a different SMTP server.
--
Gary VanderMolen, MS-MVP (Mail)
"Returned mail: delivery problems encount" <Returned mail: delivery problems
> wrote in message news:C4AA7D8D-4543-4D74-B6E8-...
>I have a problem with my Windows Mail, this is my problem
> Returned mail: delivery problems encountered
> Permanent Failure:
> 550_explicitamente_denegado_por_SPF_/_ver_http://www.openspf.org/_(#5.7.1)
>