After update to log4net 1.2.12 email encoding changed and my mail client
fail to render unicode symbols.
I think changes made for issue https://issues.apache.org/jira/browse/LOG4NET-354 brake encoding in SmtpAppender
log4net 1.2.10 use utf-8 encoding by default, below headers from email
Content-Type: text/plain; charset=utf-8
after update on log4net 1.2.12 email encoding koi8-r
Content-Type: text/plain; charset=koi8-r
I think change default encoding from utf-8 is pretty strange.
Do not use Encoding.Default, let SubjectEncoding and BodyEncoding by default be null, on email send set encoding only if field not null.