/etc/logcheck/ignore.d.server/courier-pop is in courier-pop 0.68.2-1ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | ^\w{3} [ :0-9]{11} [._[:alnum:]-]+ courierpop3login: (Connection|Disconnected), ip=\[[.:[:alnum:]]+\]$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ courierpop3login: LOGIN, user=[-_.@[:alnum:]]+, ip=\[[.:[:alnum:]]+\], port=\[[0-9]+\]$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ courierpop3login: (LOGOUT|TIMEOUT|DISCONNECTED), user=[-_.@[:alnum:]]+, ip=\[[.:[:alnum:]]+\], port=\[[0-9]+\], top=[0-9]+, retr=[0-9]+, rcvd=[0-9]+, sent=[0-9]+, time=[0-9]+(, stls=1)?$
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