GPG: There is no assurance this key belongs to the named user
In GnuPG, if you get an error saying “There is no assurance this key belongs to the named user” when trying to encrypt, you need to sign the public key.
You can sign the key by typing “gpg --sign-key user-id” at the command prompt.
Footnote: I came across this whilst migrating our e-commerce system to a new server. The system uses GnuPG to encrypt the order/credit card information and then emails it to our sales team. I’m making sure I document the process fully, so that I don’t have to spend so much time figuring this stuff out again! 
Steven said,
22 October, 2010 at 4:22 pm
Cheers, I used your solution today
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Phil Wiffen said,
26 October, 2010 at 12:58 pm
Good to know it’s still relevant Steven!
Mehr said,
1 January, 2011 at 12:25 pm
I use “gpg –sign-key user-id” command but I received error again. Then I change trust level to 5 and error message was no longer reported.
Marcus Wanner said,
3 January, 2011 at 1:15 am
Works great, thanks a bunch!
Vaibhav said,
21 January, 2011 at 10:18 pm
Thanks for your solution