Exim normally does not have much problems if we compare to sendmail. Some of Exim tweaks are as follows :
- Exim reject email is important to keep mail size normal. It does not reject email addresses as default.
- Implementation of Real-Time Blocking Lists to reduce incoming spams.
- MailScanner to protect clients from Virus.
- Whitelists, blacklists and SpamAssassin Modifications.