Your mail looks ugly in many more. Eudora in no case violates email conventions. Sorry, this is quite incorrect. The limit for a line in SMTP mail is 76 characters. How a client is supposed to react to messages containing long lines is not absolutely clear.
Some clients wrap to the display window, some display a horizontal scroll bar.
If the receiving mailer understands QP it will likely decode before any other processing, thus we are back to a long line. As your messages clearly show, you are generating long quoted lines. Since the line is not wrapped, the quote mark only exists at the start. Thus it appears, when wrapped, as if only the first part is quoted. This makes for very ugly and confusing threads.