Today we are seeing several email bounces with following error which indicates that email wasn't properly formatted by our Exchange 2010 (fully patched) and Outlook 2016 (fully patched).
] #5.0.0 smtp; 5.3.0 - Other mail system problem 550-'5.6.0 Lone CR or LF in headers (see RFC2822 section 2.2)' (delivery attempts: 0)> #SMTP#
Any idea what could be causing this?
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