I've never experienced that. When mail gets dropped, my experience is that you either receive a notice from the SMTP service or get a DMARC report that tells you about the percentage of dropped mail.
Impossible to know. But in my cases from any IP with low volume.
I.e. I have a bunch of personal servers for 10+ years, there are rarely outgoing emails from them and google happily just black-hole emails from such low volume IPs.
I'd be surprised if this was accurate. A low-volume IP might get a temporary failure code 4xx, but that's not silent. If they accept your message they intend to deliver it, or bounce it. Perhaps your return path is defective.
Google used to do this for low volume emails I was literally sending to myself by authenticating with my google smtp account credentials. I could find no rhyme or reason to it. It would claim to accept emails and they would never show up in my inbox or in spam. Sometimes they would get delivered to spam. Sometimes to my inbox like expected.
It most often involved security log snippets which would include ip addresses and hostnames that were likely already on "is a known bad actor" list.
Bug on their end? Intentional thing to disrupt spammers? I don't know.
Well, I won't contradict your personal experience, but I will say that I worked on gmail delivery for six years and if during that time it had ever come to light that any message had been accepted and not ultimately disposed of in some way, that would have been P0 and dozens of people would have dropped everything in order to root-cause and remediate that.
> Well, I won't contradict your personal experience, but I will say that I worked on gmail delivery for six years and if during that time it had ever come to light that any message had been accepted and not ultimately disposed of in some way, that would have been P0 and dozens of people would have dropped everything in order to root-cause and remediate that.
How would you even know? Last I checked, I was unable to find any support path to Gmail where one could report email-blackholing-instances and get them investigated.
This is what I wrote several years ago at the point when I gave up trying to run my own email server:
> Over the course of 2 years that I was actively using my own server to send email from the same domain and same IP, there were periods of time when my emails were landing in Gmail’s inbox. And then there were periods of time when my emails were placed in spam, sometimes outright bounced, and sometimes received and dropped without even landing in the spam folder. You could never know what Gmail would do with your email.
That's cool and all and I'll take your statement in good faith.
However, how do I as a user report that an email that was accepted by Google's own SMTP servers was not subsequently delivered to my Gmail inbox? I can't call or email support and it is a meme at this point that Google support is only accessible via social media or contacting a Google insider.