This issue appears to have related to a recent policy change in how Microsoft handles forwarding to third-party accounts. We have adjusted this policy based on their recommendation and we are no longer seeing issues for accounts that forward to Gmail, Yahoo or other third-party platforms. We will continue to test and monitor to ensure this issue is fully resolved. If you are still seeing error messages when emailing accounts that forward to third-party email providers, please contact the Help Center at firstname.lastname@example.org
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