Ask HN: Why are OOO autoreplies ever marked as junk? | Hacker News Reader

Ask HN: Why are OOO autoreplies ever marked as junk?

11 pointsgnicholas13 comments

I've noticed that OOO autoreplies get put in my junk folder not-infrequently. Why would this ever happen? I would think that junk mail filtering systems would have a rule that mail is never junk if it is from someone who I just sent a message to, and especially if the subject line is similar to that of my recent message.

Why does this ever happen? In case it matters, my mail is hosted by gmail, and I access it via Mail on my Mac. I don't know whether gmail or Mac Mail is marking this stuff as spam, but both companies should know better!

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Because it’s sometimes hard to discern from Backscatter (malicious bounce messages).

See: https://en.m.wikipedia.org/wiki/Backscatter_(email)

If the sender is using Exchange Online, this might explain why OOO replies would be marked as spam more frequently:

https://github.com/MicrosoftDocs/OfficeDocs-Support/blob/pub...

"By design, Exchange Online Protection uses the high risk delivery pool (HRDP) to send OOF replies, because OOF replies are lower-priority messages."

Perhaps people mark OOO autoreplies as spam after receiving them in reply to their mailing list posts or other mass emails.

My theory is that OOO's are (in general) short, and short messages have a tendency to end up in spam folders. The fact that people often don't use the spam buttom as a delete button probably doesn't help.

Also, Gmail is a common source of spam, and they often end up in RBL's.

Are these internal (i.e. from another Gmail user) or from another external system? I've never seen an internal (i.e. OOO from a colleague in the same organisation) marked as spam. I assume some email systems will treat their own OOO emails differently--and in fact I am pretty sure this is the case for Exchange for example. But I can see how it could happen for OOO emails from another system which would be handled simply as any other email.

My money would be on Gmail marking the email as spam. I don't recall Mac Mail doing any special spam filtering.

They're from users outside my organization. Mac Mail does spam filtering. It's in training mode when you install the OS, and then a couple weeks later it asks if you want to put it in regular filtering mode.

Very good point.

Also wonder what the reputational risk is of setting OOO - auto emails that never get opened or replied to, are often labelled as spam - and left there. Preservation of my own email reputation is the reason why I never set OOO - would recommend others do the same

I suspect it has something to do with the fact that they're all written in a pretty similar way, and, over time, you'll tend to get a good number of them. Large numbers of similar sounding messages seems like a pretty good spam signal to me.

But why isn't this spam signal overridden by the fact that I just emailed this guy? What are the odds that I happened to email a spammer?

I know it seems silly to care so much about OOOs, but I actually do want to know when someone will be back in the office, and whom I should contact in the meantime for urgent matters.

Everything I've said here, including my initial comment, was just speculation. But, if I had to speculate further, I'd guess it's because spam detectors tend not to be terribly advanced. I wouldn't expect it to consider the temporal signal of "just emailed this guy and immediately got a response back," nor would I expect it to parse the headers and check times.

Honestly, you'd probably have to actually talk to somebody at Google who works on or has worked on Gmail in order to get a real answer.

Your outgoing messages are probably not fed into the spam filter.

Apple's Mail program has a designation of Previous Recipient, which I believe refers to people I have previously sent email to.

While spam can certainly come from (or appear to come from) people in my address book, I would think it would be a good idea to whitelist emails that come from a recent recipient, where the subject line matches up as well.

Because they are junk, in the wast amount of cases.

At least I consider them as such.

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