This is VERY strange.  I have never "lost" TLUG messages--I see all TLUG messages.  After you said that, I did a search of "in:spam TLUG" just to confirm that nothing has been sent to spam, and as far as I can tell, 100% of TLUG e-mails hit my Inbox.
On the other
hand, TLUG is the only computer-related user mailing list I'm on, and I
don't have very many subscriptions, so it's quite possible my e-mail profile is very different from yours.  I'm only assuming--I use this e-mail account for RL things that include bills and shopping, but most of my other online interaction is directed to one of three other e-mail addresses on different domains, two of them self-registered for business/personal branding.  All of them run on Google Apps or some version of Gmail (the last of the four is an account on 
mail.auone.jp) so I can safely say 100% of my e-mail is handled by Google.  I expect all four of my e-mail accounts to register VASTLY different usage patterns--even though I haven't done any official tracking, just thinking about how I use them and the traffic patterns on those accounts is enough to show me there are four distinct profiles (and if you asked someone, I suspect no one would notice all four belonged to the same person).  
Part of me wants to say the variance in our usage experience has something to do with Google's personalisation initiatives, but I don't know ANYTHING about this beyond a vague suspicion, and I have zilch to back up the thought with.
Ai