This is usually feedback that they thought your message was a marketing email rather than a sales email.
i.e. not created specifically for them.
If it’s an important account then for sure drop them another message to follow up. If it’s one in a sea of many then take it as a “not right now” response just worded lazily.
I think your follow up is good. I’d probably say –
Hi NAME,
Sorry my mistake. I’m after the person who manages X.
Is that someone else in your team?
Thanks,
