display the route from your server to any email address:

exim -bt email@domain.com

send an email using exim:

exim -v email@domain.com

show the number of emails in the queue:

exim -bpc

display the mail queue:

exim -bp

flush queue:

exim -qff &

view a particular mail in the queue:

exim -Mvh msgid (for headers)
exim -Mvb msgid (for body)