Plain text e-mails should have a hard return at 80 characters.
See :
RFC822 Guideline
and also at:
RFC2822 Guideline
2.1.1. Line Length Limits
There are two limits that this standard places on the number of
characters in a line. Each line of characters MUST be no more than
998 characters, and SHOULD be no more than 78 characters, excluding
the CRLF.
Basically the sender application is following the guidelines , there is a hard return/linebreak . Sometimes if the link is enclosed with '<' url '>' it will work.
What I end up doing when required is copy the two or more lines to a text editor, join the lines until I have one complete line (removing extra spaces etc) then copy and paste into Opera.
Rather have my e-mail client follow the guidelines. Becky is doing the proper thing. In plaintext Becky shows the wrap, the HTML/Rich version is OK. Remember that fixed spaced fonts (used in plaintext) take more space than nonfixed spaced fonts.
ie: i & w take the same amount of space when you use Courier, but different amount of space if you use TimesRoman.