Is it possible to "hack" an email account so that the emails always go to Spam?

Question

I have a friend who is something of a public figure within a small sphere. She has been an object of negative attention recently in this sphere and has noticed that her emails are suddenly all going directly into the Spam folders of all her recipients. This holds true even amongst recipients on different emails services, and she has been using this email address for years without any problems.

I ask her to send an email to Mail Tester and you can see the results here (10/10 for email quality). She uses a very well known email hosting solution with a custom domain name. According to a source, she heard that apparently someone somewhere did something so that her emails would get sent to Spam.

For a particular email provider, I could sort of understand how this could work (imagine someone malicious working on the inside at Google), but I can't see how this could be the case otherwise. It's even stranger considering that some of her recipients have added her address to their whitelist and clicked on the "Not spam" button several times (in Gmail for example).

Is what my friend fears possible? If so, how?

Answer 1

Let's suppose your friend has the email jdoe@example.com.

If someone sent a lot of spam claiming to be jdoe@example.com, or even just another user e.g. jane@example.com, the anti-spam systems could conclude that “emails from jdoe@example.com / emails from example.com are likely to be spam” then affecting the legitimate mails from your friend. Somewhat similar could in theory happen as well if many people which were receiving their mails were now marking them as spam.

However, in theory this shouldn't really affect much. If your friend system has SPF and DKIM configured (which she has configured, right?), the reputation of those presumed bad emails impersonating her should be accounted separately from her real mails.

It would be quite different if her account/server was compromised, as then the bad emails would indeed "belong" to example.com.

Note however that the mail filtering engines used by the big providers are really complex, with lots of factors, and not even them know why their system takes certain actions. The fact that their are now no longer in the inbox may be completely unrelated to that negative attention. As mentioned, it may be a problem related to spam going out with their domain, but it could as well be due to someone else sending spam form an ip address not far from her server, and that affecting her mail score.

There are also fluctuations in how these systems consider mails, even with apparently no reason. If her mails were already near the line, a relatively small factor could have pushed them to the spam box. Although, given that it happened on all providers at the same time, it's likely there's some external factor driving it, even if unrelated to any of her doing. There might have been some recent configuration change on her server that affected how her emails are perceived by the systems.

Even for people working on mail deliverability, it can be hard to figure out why suddenly mails may have changed into going to spam.