sendmail@ubuntu 11.04

If you find the default installation of sendmail on ubuntu 11.04 does not work, check whether there a file called "/etc/mail/sendmail.cf.error":

Creating /etc/mail/sendmail.cf...
*** ERROR: FEATURE() should be before MAILER()
*** MAILER(`local') must appear after FEATURE(`always_add_domain')*** ERROR: FEATURE() should be before MAILER()
*** MAILER(`local') must appear after FEATURE(`allmasquerade')*** ERROR: FEATURE() should be before MAILER()

if so, do this:
$ cd /etc/mail
$ vi sendmail.mc
# move the MAILER part to the end of the file
$ make
$ /etc/init.d/sendmail reload

DONE.