Security warning, but not for everyone

See https://carpentersmail.org please.

I have client who keeps getting security warnings from their office using FF 3.6. I cannot reproduce using same exact browser at my location. Client says they are getting complaints from some people about the error as well.

I know someone who gets the error in Safari, but I do not. I know someone else, who, like me, does not get security warnings on any browser or computer.

I went to another location which used FF and indeed, I saw the error.

What could possibly be causing this. I’m running Debian Linux.

Hello,

Based on the following command…

openssl s_client -connect carpentersmail.org:443

I see this…


Certificate chain
0 s:/OU=Domain Control Validated/OU=PositiveSSL/CN=carpentersmail.org
i:/C=GB/ST=Greater Manchester/L=Salford/O=Comodo CA Limited/CN=PositiveSSL CA

The above output tells me that clients (browsers) that have yet to be exposed to that (our, Comodo) hierarchy will throw up an untrusted/unknown authority error. Please ensure that you install your certificate and any other certificates we send to you when you purchase the certificate. (Also known as fully installing the certificate )