Based on our record, Spam Check should be more popular than PixelBlock. It has been mentiond 3 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
There have been some attempts by Google to restrict the amount of information that can be transmitted this way. For example,since 2013, Google has served all images in Gmail through its own proxy servers, which could hide your location from at least some tracking applications. And extensions such as Ugly Email and Pixel Block have been developed to block trackers on Chrome and Firefox. Source: over 2 years ago
You should check to see if the messages that are being sent contain any links that would be considered questionable/spammy. You can also try taking the content of one of the messages and checking it’s spam assassin score ( https://spamcheck.postmarkapp.com ). Source: about 2 years ago
Build a clean email that passes a spam check with flying colors (https://spamcheck.postmarkapp.com/) then use a warmup service like lemwarm, inboxally or neverspam as mentioned in the other comments. Source: over 2 years ago
The issue sounds more email centric. You're likely hitting the Apache SpamAssassin limit on the remote email servers. Use https://spamcheck.postmarkapp.com/ to check the score of emails you've had declared spam, and follow recommendations to improve. Source: almost 3 years ago
Ugly Email for FireFox - Get back your email privacy, block email tracking
Referrer Spam Remover - Remove spam bots from your Google Analytics data
Mailpanion - Track your email clicks & prevent others from tracking you.
Phishero - Test your organisation's resiliency towards phishing attacks
Inbox When Ready - Protect your focus... hide your Gmail inbox by default
Re:scam - I’m an AI chatbot created to send scammers a message.