I can't change my Dropbox email address to a new one, because it's taken, even though it's not.

Thanks for your post, goofansu! 

Please keep in mind that this is a public forum, so I wouldn’t recommend posting your email address here.

Now, as for the new email address you’re trying to use, can you check its inbox (and spam folder) and let me know if you can see any old emails from Dropbox there? 

We can take it from there.

Hi Nancy​, I cleaned up all emails in the new email address, so I don't know whether it is signed up before. I assume it is not taken because Dropbox guides me to sign up when I tried to sign in using the new email address.

In this case, can I send you an email in order for us to have a closer look into this goofansu? 

Megan​ Sure, please, thank you.

Just sent you the email goofansu! 📩

Reply back as soon as possible, and we'll take it from there. Thanks! 

The problem was solved thanks for your supporting.