Restart exim, when executing a "ps fax" from the console, I see that the change has come into effect but do not run the retry every 1 minute.
5806 ? Ss 0:00 /opt/exim/bin/exim -bd -qff 1m
5807 ? S 0:00 \_ /opt/exim/bin/exim -qff
5875 ? S 0:00 | \_ /opt/exim/bin/exim -qff
5876 ? S 0:00 | \_ /opt/exim/bin/exim -t -oem -oi -f <> -E1h3bJS-0008HE-7L
5815 ? S 0:00 \_ /opt/exim/bin/exim -bd -qff 1m
5816 ? S 0:00 \_ /opt/exim/bin/exim -bd -qff 1m