We are using Gmail Postmaster tools (I work at a small ESP), and while this tool is certainly useful for diagnosing rejections, delivery to Gmail inbox / promotions is still a black box.
In our case, a number of IP addresses we are using started showing up as "bad" in Postmaster tools, despite having no increase in complaint rates (actually, in Spam rate dashboard it shows 0.0% for the past 90 days). We have implemented Gmail feedback loop headers into outgoing emails to diagnose the issue, but the Feedback Loop dashboard also does not show any data.
All of these IPs have a Senderscore reputation in the high 90s and deliver perfectly fine to all ISPs, except Gmail. Contacting Gmail team through their form also yields no response.
My takeaway from this situation is that once Gmail starts not liking your emails for some obscure reason, you have practically no way to fix that, apart from getting a new IP / sending domain and starting to build sending reputation from scratch.
In our case, a number of IP addresses we are using started showing up as "bad" in Postmaster tools, despite having no increase in complaint rates (actually, in Spam rate dashboard it shows 0.0% for the past 90 days). We have implemented Gmail feedback loop headers into outgoing emails to diagnose the issue, but the Feedback Loop dashboard also does not show any data.
All of these IPs have a Senderscore reputation in the high 90s and deliver perfectly fine to all ISPs, except Gmail. Contacting Gmail team through their form also yields no response.
My takeaway from this situation is that once Gmail starts not liking your emails for some obscure reason, you have practically no way to fix that, apart from getting a new IP / sending domain and starting to build sending reputation from scratch.