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Fix SMTP on magento 2.3.3

Please unzip  file  to folder contains magento code

Then run command 

patch -p1 < EmailMessageInterface_2.3.3_backward_compatibility_composer-2019-10-30-10-20-09.patch

https://magento.com/tech-resources/download#download2333

 EmailMessageInterface_2.3.3_backward_compatibility_composer-2019-10-30-10-20-09.patch.zip