Debian upgrade

dpkg: error processing qpopper (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 openbsd-inetd
 netbase
 exim4-base
 exim4-daemon-light
 at
 exim4
 ftp
 mutt
 nfs-common
 pidentd
 lpr
 mailagent
 ppp
 pppoe
 pppoeconf
 uw-imapd
 qpopper
E: Sub-process /usr/bin/dpkg returned an error code (1)
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