gentoo-overlay/mail-mta/exim/files/exim-submission_at.service

# It doesn't make sense for this to be separate from exim@.service
# However, I couldn't think of a way to have two .socket files point
# to it ([Socket] Service= is rejected if Accept=yes is set).

[Unit]
Description=Exim Mail Daemon per-connection server (message submission)

[Service]
ExecStart=-/usr/bin/exim -bs
StandardInput=socket
StandardError=syslog