Sylpheed can't verify signature?

[Dallam Wych]

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Hi List,
A quick question please. Gnupg is new to me, I have only been using
it for a few weeks now. For numerous reasons I like the idea that
mail is signed and that I can identify that it really did come from
where it claims. However, on one (of the dozen) lists I subscribe to
someone has complained that I sign my mail when I post. They say
that Sylpheed pops up an annoying dialouge box ":can't verify
signature from?".
Could someone please enlighten me as to why this is? I have a dial
up account here, so at peak times I fetch my mail and disconnect and
read it offline. This is the only time I get something like
signature can't be verified. I know that my sig is verifiable, so is
his mailer misconfigured or is he just offline and can't be asked to
ever verify it? I don't know anything about Sylpheed, except that
apparently it has pop up dialouge boxes :)
Regards,
Dallam
--
Dallam Wych              dallam@btopenworld.com
1024: A89A2371         "Ipsa scientia potestas est"
2717 4EB8 461D 743B 47CF  Registered Linux User
0D68 C32A 5CDE A89A 2371  counter.li.org:213656

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