How does one add a Yahoo! Mailhost? After submitting, with all the headers, I still get the following message:

Sorry, SpamCop has encountered errors:
Headers not found.

It appears you did not provide all email headers. Please consult this FAQ
for more information on getting full headers from your software, then try
again.

http://spamcop.net/fom-serve/cache/19.html

Based on some recent traffic here, submitting via email is not working for some setups which have not been fully defined. That wiill also affect the Mailhost submission. I know I was able to submit via email one message at a time from the "original webmail" application by holding down the control key (Windows) while clicking the Forward button while in the message.

You can paste the headers into the web page if you can find them. You may also need to follow the first pinned item in this topic to contact the Deputies.