Email click after soft bounce with hard bounce code

[Kanako_Tone2]

I came across handful leads clicking our emails right after the emails were delivered. And here's the most bizarre example I found.

So, this lead has gotten Soft bounce with error code 550 [internal][oob] The response text could not be identified. FYI, soft bounce category was 9 and sub category was 9999.

According to several articles on this community such as this, sub category 9999 as well as error code 550 means this person's email address does not exist in the recipient's email server. So I guess no real human beings is receiving this email. And there's click activity...

My questions are;

Q. who is clicking soft-bounced emails that are marked as not-found?

Q. if this click is a response from a bot, why is there so much time delay between bounce and click email?

Q. Is there any way to find these "soft bounces" easily, after it has happened? (I found this article and will implement the system, IF there's so many instances like above. I'd like to investigate first but it's so tedious to look into lead activity history one by one).

[SanfordWhiteman]

The message was received by an intermediate scanning gateway and immediately stored.

Attempting to relay to the final destination server resulted in a 550, which becomes an OOB bounce.

Later, stored messages were re-scanned on the gateway. Presumably this happened before the messages were completely purged.

It's a confusing situation, but not outright bizarre because it all happened within 24 hours.

Yet another reason to not trust ​Clicked Email, ​too.

[Kanako_Tone2]

Sanford Whiteman​, thanks for your reply! If I'd seen only the second example in which Delivered, Soft Bounce then Click happened all in 5 mins, I'd have concluded that it was just a typical anti-spammer behavior, But in the first example, the click activity happened after 24 hours of Delivered & Soft Bounce. (both screenshots are from the same lead). Is it still common behavior by these anti-spam bot?

[SanfordWhiteman]

As I explained, there's no reason to think that all anti-spam quarantines behave in the most streamlined way.

Some quarantines re-scan stored messages after a period of time, and in this case it appears this happened even though the earlier relay attempt failed, meaning the recipient could not accept mail. The message was left in storage for whatever reason.