I'm in a bit of a dilemma with outbound mail with the Ironport and Office 365. Some domains do not receive emails from my organization when we send it through the ironport. If I turn off the outbound connected and let outgoing emails bypass the Ironport it works fine. I spoke with Microsoft support and they said it had to do with ESMTP and that I should disable or bypass that on the Ironport since Office 365 already does it. I cannot for the life of me figure out how to go about doing this in the Ironport and I couldn't really find anything about it in the manuals. Has anyone run into this situation or can anyone point me in the right direction so that I can resolve this? I really need to keep outbound mail flowing through the Ironport because we are required to send secured email attachments. Thanks.
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