I've noticed that some e-mail marketers send emails with subject lines like these:
[MARKETING] My subjectline
Why do they do this?
Hi Chrissy, welcome to the forums! In some regions, a subject line prefix is either considered best practice or required by law - for example, email marketers in China prefix their subject lines with [ADV] (or the simplified Chinese equivalent), to denote their emails are marketing messages. In the US, prefixes are generally only used on email with adult content.
Thanks, Chrissy! Always happy to help out if you have any questions about this :)
Great answer. This was very interesting.