Moving mail before deleting account on Mac mail

Hi all,

I've got an email account that I want to remove (but keep the emails) on Mac mail that was a POP account so the emails aren't on a server, they're only on this Mac. The inbox has 45,000+ emails in it, and doing an Export of the mailbox is only exporting around 15,000 due to the 2.15GB export limit.

So I've run an import which has got the 15,000 emails in, and I've selected the remaining 30,000 in the inbox and "right clicked" and clicked "move", and moved them to the same folder as the 15,000. All looks good as I have all 45,000 emails in there now. However, I'm just a bit concerned that when I removed the original mail account, it's going to take the 30,000 I moved rather than exported with it?!

Is this the case? Moving the mail rather than exporting / importing almost seems to easy to be true! There's not many references online to people opting for this method over an import. Are there reasons against this method?