Email output issues after migrating from 11g to 12c

Hi everyone,

After migrating from BI Publisher 11.1.1.7 to 12.2.1.3 we've noticed that all letters are sent with Content-Type "text/html" format, instead of "text/plain" as it was before. Is there a way to change back Content-Type of emails? Because now Outlook shows them without line breaks.

Also, BIP corrupts names of attachments if they are long and have cyrillc letters in them. So users receive emails with attachments named like "=UTF-8B0JfQstGW0YIg0LQviDQvdC10LRgNC40LnQvdGP= =UTF-8B0YLQuNC8INGA0LDRhdGD0L3QutCw0LwueGxz=".

The OS we have is Windows Server 2016.

Thanks in advance.