Solaris 2.x uses the "Content-Length:" header to tell the MUAs
where messages should be split. Unfortunately, no-one else
understands this convention. Instead, the old convention, ``split
on "From " lines'' is used most of the time. Those mail readers
expect extra lines with "From" to be escaped with ">".
Workaround: add "E" to the mailerflags of the local mailer.
Edit /etc/mail/sendmail.cf on your Solaris machines, add E to
F= on the line that reads:
Mlocal, P=/bin/mail, F=flsSDFMmnP, S=10, R=20, A=mail -d $u
so that it becomes:
Mlocal, P=/bin/mail, F=EflsSDFMmnP, S=10, R=20, A=mail -d $u