[zAy0LfpBZLC8mAC]

> Sometimes emails have "<br>" in them and sometimes they have "\n".

One of those should have an HTML MIME type, one should have a plaintext MIME type. The decoding is specified in detail in RFCs and W3C recommendations, please follow those rather than try to implement this using try and error.

> Not everyone uses the RFC standards!

That is unfortunately true, ...

> I thought the RFC said that a subject can only be 78 chars long.

... and one of the major reasons why is because people think but don't read. There exist all kinds of crazy myths about the content of RFCs, which is how all those broken implementations arise, this seems to be one of them--but feel free to point out which RFC says this where, in case I really have missed it.