Mavericks and Yosemite marks mails in multiple accounts as read I have 2 accounts configured in my Mac mail. alex@ and orders@

If for example I receive an e-mail with TO: alex@ and CC: orders@ it will go to both e-mail addresses. So far so good, but when I read only one copy (either from alex@ either from orders@) the mail app marks as read both of them.

This is happening even if I have Gmail account or Yahoo it does not matter the server.
Any idea of how to stop this? I just need to mark as read the e-mail I read from the specific email account, not from all of them.
Strictly speaking, You have read it.

I've noticed recently that if I get duplicate emails to 2 accounts, Mail is actually appearing to merge them into one email [at a user-level anyway, idk about behind the scenes]

I know of no way round this, so maybe try using Flags instead of the 'read' indicator. More work, but more reliable.