invalid digital signature

[Guest]

I'm a home user that is a tad ignorant on digital signature troubleshooting. I received two e-mails that contained "invalid Digital Signature" in the preview pane, and said for details to open the mail. This is the first time I have ever received e-mail like this and these were from a friend who normally sends several e-mails a day. Suspicious as I am, I deleted them instead of opening them, particularly since I have never seen this type of message (?) error (?) before. I have searched all the security sites I can find, and they all tell you how to do digital signatures, but nothing tells what to do when one is received. I think whatever it may be, that I am safe: my MS patches are all up to date( I keep them that way) and I have active virus protection via Norton, email scans in/out, auto liveupdate, etc. I have detected virus's from others when e-mail comes in and I have been able to trace them back to get the victim to get rid of the virus and get them on virus protection, but I'm not sure what to do about this. Is it "safe" to open when it has this message and what could be the possible culprit? - yes, it means it's not valid, but is there a known virus, worm or something out there causing this type of effect? Thanks in advance for your replies.

 

[Touch Base]

"This is the first time I have ever received e-mail like this and these were
from a friend who normally sends several e-mails a day. "

Did your friend tell you that he would be sending emails with a digital
signature? Do you have or has he sent you a copy of his digital signature?

a.. When you receive a digitally signed message, the sender's digital ID
will be automatically added to your address book.

How Digital Signatures Work: Digitally Signing Messages
http://www.developer.com/java/other/article.php/3092771

From your friends perspective:

http://support.microsoft.com/default.aspx?scid=kb;EN-US;q331923
OLEXP: An Overview of the Cumulative Update for Outlook Express 6.0 SP1

"You Receive an Error Message for an Invalid Digital ID When You Send
Messages That Are Signed with Esign Certificates.

When you use Outlook Express 6.0 SP1 to send a message that is signed with a
signing only Esign certificate, you may receive an error message for an
invalid digital ID. If you ignore this error message and send the message,
the message is sent as expected. This issue does not occur if you import the
twin Esign encryption only certificate (of the dual certificate pair)."

I'm a home user that is a tad ignorant on digital signature

troubleshooting. I received two e-mails that contained "invalid Digital
Signature" in the preview pane, and said for details to open the mail. This
is the first time I have ever received e-mail like this and these were from
a friend who normally sends several e-mails a day. Suspicious as I am, I
deleted them instead of opening them, particularly since I have never seen
this type of message (?) error (?) before. I have searched all the security
sites I can find, and they all tell you how to do digital signatures, but
nothing tells what to do when one is received. I think whatever it may be,
that I am safe: my MS patches are all up to date( I keep them that way) and
I have active virus protection via Norton, email scans in/out, auto
liveupdate, etc. I have detected virus's from others when e-mail comes in
and I have been able to trace them back to get the victim to get rid of the
virus and get them on virus protection, but I'm not sure what to do about
this. Is it "safe" to open when it has this message and what could be the
possible culprit? - yes, it means it's not valid, but is there a known
virus, worm or something out there causing this type of effect? Thanks in
advance for your replies.