I'm running a small online shop and I noticed that in the past days I had a lot of "recipient not found, email cannot be delivered" messages in my inbox. I realized that these are bounces of emails my shop sent.
At first I paniced and thought the store was compromised and sending spam, but after some investigation I found that a lot of russian bots actually registered spam user accounts with mostly legit emails which then got all the spam. The only "customizable" parts these emails contained was the "From" field of the emails so they were all in the form of "PAYOUT_TO_YOUR_NAME_$3OOOO_HER example.com <mail@example.com>". After adding a captcha this went away, but it sounds like it was also part of a similar attack.
At first I paniced and thought the store was compromised and sending spam, but after some investigation I found that a lot of russian bots actually registered spam user accounts with mostly legit emails which then got all the spam. The only "customizable" parts these emails contained was the "From" field of the emails so they were all in the form of "PAYOUT_TO_YOUR_NAME_$3OOOO_HER example.com <mail@example.com>". After adding a captcha this went away, but it sounds like it was also part of a similar attack.