eimsmail is intended to be parameter compatible with common versions of the sendmail command. Currently it supports the following parameters:
-B: specify the content encoding, 7BIT or 8BITMIME
-i: EOF is end of message, rather than a line with a "." on it
-r: sender address (SMTP MAIL FROM)
The -t parameter, which has sendmail extract the list of recipients from the headers of the message, is not yet supported. Many other parameters are ignored or not supported.
To set up eimsmail, copy the eimsmail command to somewhere suitable and give it suitable permissions. Typically you will want to put it somewhere like /usr/sbin and give it owner, group, and world read and execute privileges (chmod 555). If you want to completely replace sendmail with eimsmail, rename or delete the sendmail command, and replace it with a symlink to the eimsmail command.
eimsmail works by saving the message in an appropriately formatted file in the EIMS Incoming Mail folder. To find the Incoming Mail folder, it looks for the path in a file at /etc/eimsmail.conf. An example eimsmail.conf is included, the path does not need to be quoted if it has spaces in it.