I am using http://validator.nu/ to check the following web page:

http://origin.opc.ncep.noaa.gov/opc_mobile_cj.php

I get this error message:

Bad value mailto:ncep.list.opc_web@noaa.gov?subject=[OPC%20mobile%20feedback] for attribute href on element a: Illegal character in query component.

The validator fails on this exact HTML syntax:

Feedback: <a href="mailto:ncep.list.opc_web@noaa.gov?subject=[OPC%20mobile%20feedback]">ncep.list.opc_web@noaa.gov</a><br>

However, if I remove the bracket characters [ and ] in that syntax so that the HTML is now the following:

Feedback: <a href="mailto:ncep.list.opc_web@noaa.gov?subject=OPC%20mobile%20feedback">ncep.list.opc_web@noaa.gov</a><br>

then the validator does not report errors.

It appears that a special character such as a bracket or a parenthesis before the quote in the closing a href tag is causing the validator to report an incorrect error.

I believe the existence of the bracket characters should not cause the validator to fail.

Thank you for making this tool available.

Regards,
Christopher Juckins