.NET Weird character encoding issue

Our globalization mechanism stores error messages in a SQL 2005 DB.

Some of the error messages are used as subjects on email messages sent to the development team.

Recently, with no clear reason, we started receiving emails with strangely encoded subjects, such as:

=?utf-8?B?Qm1mQm92ZXNwYS5Qb3NUcmFkaW5nRXNwZWNpZmljYWNhbyAtIFN1Y2Vzc28gbm8gcmVwcm 9jZXNzYW1lbnRvLiBEYXRhIFByZWfDo28gPSAzMS8wMy8yMDEwIDAwOjAwOjAwIC0gTsO6bWVyby BkbyBFdmVudG8gZGUgTmVnw7NjaW8gPSAxMDAyIC0gQ8OzZGlnbyBOYXR1cmV6YSBkYSBPcGVyY cOnw6NvID0gQyAtIFNlcn...

We don't have any clue on the reason this is happening, nor which encoding pattern is being used here (maybe utf-8?).

I'd really appreciate 开发者_开发百科some help.

That is UTF-8 reencoded as Base64

("BmfBovespa.PosTradingEspecificacao - Sucesso no reprocessamento. Data Pregão = 31/03/2010 00:00:00 - Númer...)