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Using Microsoft Outlook for Mac version 16.54 Microsoft 365 and receiving bounce back when "New Outlook" toggled on but no bounce when toggled off. A Gmail account does not have the same issue.
The bounce error is:
SmtpSubmissionPermanent5XXException: Smtp submission failed. Server 'smtp.cox.net' Port '465'. --> Unexpected SMTP server response. Expected: 250, actual: 503, whole response: 503 not availableFailure code: 5513
Updated the password per Cox' support site, but didn't resolve. When sending with the "New Outlook" toggled on, the above bounce happens but toggling off "New Outlook", email sends fine.
No problem receiving emails either way.
Checked for Office update and it says Office is up to date.
I would try recreating the Outlook profile. Also make sure your AV and VPN/Proxy is disabled.
i did try a new profile. i'll try the AV option next. thx!
curiousGeorgia said:receiving bounce back when "New Outlook" toggled on but no bounce when toggled off
Rereading the post and being not so centered on the bounce error number, I wonder what the "New Outlook" button does? Do you mean in the right/Control click menu? Or is that just what you have your profile named?
It's actually a feature set you can turn on or off. I uninstalled the McAfee Total Protection and that didn't help. I've also tried with SMTP ports 465 & 587 and with and without @cox.net in the username. Same problem. When toggled off, I send/receive with no problem. I'm feeling like it is a problem with how MSOFT is trying to implement the cloud part of this and Cox having some kind of communication issue. When I logged into outlook.live.com there were several messages saying:
From: Microsoft Outlook
Sent: Friday, October 29, 2021 1:14 PM To: Subject: Please update your credentials for the account [redacted]@cox.net
It looks like we don't have permission to get email for [redacted]@cox.net.
The last successful sync was on 10/25/2021 4:48:42 PM UTC.
How to Fix It
If you're using the new Mail experience in Outlook.com:
If you're using the Classic version of Outlook.com:
Note: To stop receiving these notifications, please remove or fix the connected account that's not syncing.
Microsoft will never ask for your password over email.
This system notification isn't an email message and you can't reply to it.
Sorry, I don't know much about Outlook. Besides Outlook Exchange at work, I use Gmail and the web client. Perhaps someone else here has more experience can chime in. Good luck!