The best replacement for exim is sendmail.

The best alternatives to exim are rated as following:
★★★★★  sendmail
★★★★  postfix
★★★  qmail
★★  dovecot
★  ssmtp
★  postfix debian
  procmail
  powermta
  postfix ubuntu

Your alternative for exim is not listed? Suggest!
Speaking about exim, one probably shouldn't forget about spamassassin.

Other search terms related to exim and their ratings are:
★★★★★ spamassassin
★★★ clamav
You have in mind a companion for exim and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of exim in all years. Click on graph for more.
exim
sendmail
postfix