I have not found a solution to this problem. I have implemented SPF, DKIM, and DMARC, and have quadruple checked to ensure they are valid. I have a reverse DNS (PTR) record for my ec2 server so that the result of
dig -x 188.8.131.52 returns something like this
184.108.40.206.in-addr.arpa. 299 IN PTR invoice.mydomain.com.,
although I don’t believe that is an issue because the headers are the same as without and do not reference ec2 server’s IP as “sending” mail server anywhere. I did add my IP to the SPF record as well which doesn’t change anything, again because all the messages still are sent from smtp.gmail.com. My SPF now reads
v=spf1 ip4:220.127.116.11 include:_spf.google.com ~all.
As far as AWS being the culprit, I do not believe this to be the case because while they do filter port 25 and limit ability to send lots and lots of email from ports 465 & 587, I do not see anything in the headers to suggest any kind of machine learning/filtering being done, but I’m no expert in reading email headers so I could be wrong.
As of today my messages to Gmail accounts are still being marked as Dangerous Spam, with links disabled and a giant RED Banner at the top of screen that says:
This message seems dangerous
Similar messages were used to steal people's personal information. Avoid clicking links, downloading attachments, or replying with personal information.
Then at the bottom of the screen, this message is displayed in orange banner:
Downloading these attachments is disabled. This email has been identified as phishing. If you want to download these and you trust this message, click "Not spam" in the banner above.
Google has several settings available to domain administrators which affect these messages. Depending on how the admin for the receiving domain has configured determines whether the messages make it through or not. The problem is that the default is “enabled” so I suspect most folks will have these “Safety” features on meaning they will not see my invoices/quotes/etc.
These settings can be found here:
Gsuite Admin > Apps > Settings for Gmail > Safety There are 3 settings:
- Attachments - Additional policies to protect against malware in emails.
- Links and external images - Additional settings to prevent email phishing due to links and external images.
- Spoofing and authentication - Additional settings to reduce phishing attacks due to spoofing and unauthenticated emails.
Each of the 3 settings above has multiple sub-levels and options too. I have been going through them to find out which specific one is the culprit, but it is time consuming and so far results are not definitive as they seem to change. The only thing that is consistent is the message content. The way gmail handles them varies.
I have been receiving DMARC reports from Postmark, which is great tool and feature they offer, and there does appear to be several “Unknown sources”, but there is nothing to be done about it according to Postmark’s FAQ and help guides.
I am currently waiting for Amazon Support to remove email sending restrictions from my server, as part of getting Amazon SES going. However, their support tells me that the only limits imposed are on Port 25. Period. Regardless, I made the request and am jumping the hoops.
How about that offer to look at some email headers?