Hi C Trocado,
I don't know your question clearly from your description, I have some things to confirm with you:
1. What is the last upgrade, update your system, App or Exchange?
2. What account type are you configure in this App, Exchange, POP3 or IMAP4?
3. Do you mean you cannot use an Exchange 2007 mailbox to send mail to the mailbox in your mail App, but you can use the mailbox in your mail App to send mails to Exchange 2007 mailbox?
Regards,
Kyle Xu
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