HTML message is corrupted if <&quote;> is included

Symptoms 

When you send a calendar invitation in HTML format from Exchange Online to Microsoft Exchange Server on-premises, and the HTML includes the <&quot;> tag, the style attribute in the message is corrupted and the message loses its formatting. 

Resolution 

To fix this issue, install the following cumulative update: 

• Cumulative Update 15 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019