UNTRUSTED signature in GPG

[Fernando Shayani <fernando_shayani () yahoo com br>]

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Hash: SHA1

I'm using GPG with Enigmail and WinPT on WinXP Pro.

Every message that I receive from anyone that is signed, the EnigMail
says that the signature is GOOD, but is UNTRUSTED!
How can I change that?

When I list my keychain with WinPT, I can see the person's public
signature, but I cannot change the ownertrust because it says that the
key is "non-valid".

What is that? What can I do?

Thanks!
Fernando
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Version: GnuPG v1.2.1 (MingW32)

iD8DBQE+rJV1/fWISJQncD4RAh61AJwOgICX1LReK24788ZDsHzILRLvNQCdH4F0
2880RVQtmej/hoGA2IJ5RYc=
=2oO7
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