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If your email service supports Sieve scripts (for example, Fastmail or Proton Mail), you can use this filter [1] that I made. It's very aggressive and will block all emails that originate from Zendesk, so you'll need to disable it whenever you're actually expecting mail from Zendesk.

[1]: https://gist.github.com/hampuskraft/780c8fbcc4042689153533ef...

Same here, I removed my email address from Github and all other public pages

Zendesk’s mailserver reputation has got to be extremely poor by now. I think they will have trouble with deliverability after this is over. Got about 50 of these today and nearly all of them were categorized as spam before they made it to the inbox despite being nominally “legit”

Unfortunately mail server reputation's based on how rich and important you are and not how much spam you send

Glad I'm not the only one. It seems to use {popular website without tld}@example.com as a pattern, so I'm getting a lot via my catch all address even if I haven't used the specific inbox yet.

I've got four emails, and I've no idea what’s going on. (I have a public email address on GitHub)

It seems to have started two weeks ago. A spammer realized that one can find a Zendesk‐based help forum, open a new ticket without an account, fill the ticket with spam URLs, and put an email address scraped from GitHub commit logs in the author email field. Zendesk would “helpfully” send the “author” the contents of the ticket, becoming in effect an open relay for spam emails. Two weeks ago is when the spammer started the attack in earnest: I received hundreds of these spam emails, typically one or two per Zendesk‐hosted help forum, sent to email addresses that I’ve only ever used on GitHub. It was discussed a bit on HN: https://news.ycombinator.com/item?id=46685768

Since then, Zendesk seems to have strengthened their system so that opening a ticket requires account activation first. Leading to today, when I’ve received thousands of signup attempt emails (again, typically one or two per Zendesk‐hosted forum). This is way more emails than I got last time. I hypothesize that the spammer is doing a “last gasp” attack: now that Zendesk has burned the exploit by no longer including the ticket text in the emails, the spammer is trying every Zendesk site it knows in hopes that some of them are slow to update and still forward the ticket text to the victim.

What would be the goal of all this? Just for the fun of it?

For a company utterly dependent on email, Zendesk came across to me as very naive about email sending.

I did a Zendesk integration shortly after working on a general overhaul of our email at a previous company. The overhaul involved separating out our different types (transactional, marketing, support, etc), and then implementing best practices on deliverability for each of them. Not your day-one email setup, but we were still a small company.

The comparison to Zendesk's approach was astounding. Assuming you don't want to use a Zendesk address (we didn't, customers thought it was dodgy), the email setup they let you do was bad, and their support folks had no idea about any of the details. DKIM, SPF, etc, was all alien to them. Ironically they had pretty bad support in general.

I worked at Zendesk on the email team. I think that's just support being support. The core engineers knew what they were doing.

I transitioned Zendesk from their original Exim-based ingress/egress SMTP services to Postfix and set up all the DKIM and SPF stuff long before there was ever a mail team. I worked regularly with large email providers to ensure our egress CIDR blocks were clean.

I like to think I knew what I was doing. :-)

That's good to know you knew what you were doing! However the product also didn't appear to expose any of the control we needed to have a good email setup. Maybe this is because we weren't paying enough (mentioned in another reply), but we were also never directed to pay more despite asking for this sort of control.

> DKIM, SPF, etc, was all alien to them. Ironically they had pretty bad support in general.

So basically good old fashioned "quality" enterprise shitware.

Not necessarily, our support team kinda loved it. I used the interfaces and it was pretty good software in many ways. They just didn't seem to be very capable when it came to medium complexity email setups. Many of their setup guides literally tell you to log into support address Gmail and set up a forwarding rule to send everything to Zendesk.

I suspect the issue is that we weren't paying enough. We had maybe 10 seats. I bet if you're buying 1000 seats a bunch of Zendesk engineers turn up and configure everything for you, but with the robust email setup needing that engineering time on their side to configure... so I guess in that way it may be Enterprise shitware.

Thank you for letting us know, got a bunch of those in the last two hours, like one each five minutes, but it seems they've stopped (at least for now).

I'm getting emails titled "Activate account for ...", and addressed to random names of web services at my domain (e.g. reddit@example.org). Also Twitch-related names like pog, kekw and xqc.

Also super annoying are crypto scams sent from an Italian ISP's (tiscali.it, shame on you) email service, even though I tried to contact the ISP, but that's unrelated to this.

Yep, same here, with those exact prefixes...

I got 201 activation emails in 98 minutes.

I've also received about 40 messages, on mail adresses I've never used before.

Yeah same here, specifically on my (public) GitHub email address

I've been getting some of these these to my wildcard domain - I've had sign-up messages sent to diddy@<domain> and epstein@<domain>, which is... odd. And no, I can't say I've ever used those addresses.

I had several sent to these local parts as well.

sounds like a sign up bomb for github addresses, these are typically used to hide new login notifications by threat actors

Received 15+ in 10mins on a public email (dropbox, soundcloud, gitlab, tidelift etc). Then just started hitting handles on the domain ( diddy@, epstein@ ). Just placing an aggressive block for "Activate account" and "zendesk" in content for now

Same. I've gotten over 30 I think.

Started getting these too just now

Huh. I thought this was targeted to me in particular, because it started coming up with new aliases at my Firefox Relay subdomain, and then only once I started blocking them it started using plus-addressing on my gmail. Annoying.

I got about 50 of these this morning and thought it was a disgruntled HN user.

I just got 50 emails lol, this really sucks, phew glad i am not alone