I've been on both since before I bought my Pantera 21 years ago! And I'm glad both exist! There are different people one each - not sure why someone wouldn't want to be on both as I find I can't get enough DeTomaso content/info each day! 
In any case, subscribe to the mail list at the link Joules provided.
Turn off email notifications and forwarding.
Bookmark the link Larry sent. When you want to see any updates throughout the day, just click the "View by Date" option, and every message/post appears in chronological order.
When you want to ask a question, just send an email to to detomaso@server.detomasolist.com with a meaningful subject line. If you want to share something that is not Pantera related, preface the subject with "NPC" which means No Pantera Content.
To reply to a post, copy the subject to your email subject, and copy the relevant info you want to reply to or comment on and paste it into your email message beneath your comments. I always preface it with --- original message --- so it's clear to folks what I'm responding to so they don't have to go find the original message.
The DeTomaso Mail List search capability is almost useless! The best way to search the mail list is to use Google. Here's an example of a Google search of the site if I want to know what Porterfield brake pads I need:
site:http://server.detomasolist.com/pipermail/detomaso/ porterfield
Your search term should be the last word in the string, separated by a space from the site url. If you need to search a multiple word phrase like "heater valve" enclose it in quotes.
Both forums have a place, and there are a lot of great people and good information in both places!