I'm using Chrome BTW. I didn't see any new errors or warnings when I clicked Send, but I did get 3 errors and 1 warning when loading the email activity page:
Warning: "[Deprecation] Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check xhr.spec.whatwg.org/."
Error: "Refused to set unsafe header "Content-Length" global.ashx?ver=-326521812:6741"
The other 2 errors were the same.
I tried it again in Edge and got 1 Error and 1 Warning when loading the page:
Error: "SCRIPT5022: Error : Cannot inject element to DOM marsloader.js (1,44472)"
Warning: "HTML1514: Extra "body>" tag found. Only one "body>" tag should exist per document. main.aspx (1137,1)"
When I clicked the Send button in Edge, this was added to the end of the console: "SCRIPT7016: SCRIPT7016: Use of XMLHttpRequest with the synchronous flag set to true is deprecated due to its impact on user-perceived site performance."
IE 11 gave 2 warnings and 2 errors while loading and nothing when clicking send:
Warning: "DOM7011: The code on this page disabled back and forward caching. For more information, see: go.microsoft.com/fwlink
main.aspx"
Error: "SCRIPT5022: Error : Cannot inject element to DOM
marsloader.js (1,44473)"
Warning: "HTML1514: Extra "<body>" tag found. Only one "<body>" tag should exist per document.
main.aspx (1137,1)"
Error: "SCRIPT1002: Syntax error
ClientApiWrapper.aspx (137,17)"
Unfortunately, that doesn't mean anything to me.