imapd returns exit(1) on Autologout.This creates gazillions of, eg.: Oct 3 15:44:35 host inetd[27281]: pid 9848: exit status 1 Oct 3 15:44:59 host inetd[27281]: pid 9791: exit status 1 Oct 3 16:20:58 host inetd[27281]: pid 10006: exit status 1 messages in /var/log/messsages. It didn't do this before, afaik.
Examining the sources to 4.7 shows that this is the case whenever imapd exits as a result of anything but a LOGOUT command from the client (including interrupts, HUP signals, loss of connection, and idle timeouts). The sources to 4.5 appear to be identical in this respect.