Details and link on the Europe forum:
https://community.ricksteves.com/travel-forum/general-europe/low-fares-to-europe
On the other post the link is for a site called TravelZoo - I would be very suspicious of it. You can find the fare sale on the TAP Portugal web site - prices do look amazing compared to what we're seeing right now - for next winter/early spring.
On the other hand, maybe less of a bargain after you drill down to the lengths of some of the flights.
I'm a traveler of modest means. I've been fearlessly clicking on Travelzoo for, oh, maybe 20 years and with all kinds of good results and no ill effects.
It's not just about airfares to Europe... it's an awesome site for finding low-priced travel deals of all kinds... cruises, vacations, rentals, airfares... to destinations all over the planet. Even when I'm not so interested in traveling, I love to open up their emailed "Top 20", a compendium of the previous week's best travel deals, which shows up in my inbox every Wednesday - I make a few mental notes about travel trends and pricing and occasionally get inspired to make tracks again.
The Travelzoo page I linked to provides a brief summary of the TAP deal up front. It also provides a direct link to the deal at the TAP airlines site if you. Travelzoo does not sell tickets or reservations or take your money for anything, AFAIK. Read about Travelzoo here if you wish:
There are some great deals if you don't mind a layover of 20 or so hours somewhere. Hard pass for me.
No matter what book direct
No that random site you just found offering a much better deal than the airline is not the cheap airfare fairy that gets deals directly from the airline you can’t get.
If you don't find the flight that suits you at the TAP page, look elsewhere, of course. All such advertised sales are a mixed bag to one degree or another.
I easily found a direct flight NY > Porto next spring for $440. SFO > Porto for $511 with 2-hr. stopovers.
Again, Travelzoo doesn't sell flights. TAP does. Book direct with TAP, as Travelzoo suggests.