For openSUSE Leap 42.3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/spins:invis:benno/openSUSE_Leap_42.3/spins:invis:benno.repo
zypper refresh
zypper install perl-Mail-IMAPClient
For openSUSE Leap 15.1 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/spins:invis:benno/openSUSE_Leap_15.1/spins:invis:benno.repo
zypper refresh
zypper install perl-Mail-IMAPClient
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/spins:invis:benno/15.6/spins:invis:benno.repo
zypper refresh
zypper install perl-Mail-IMAPClient
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/spins:invis:benno/15.5/spins:invis:benno.repo
zypper refresh
zypper install perl-Mail-IMAPClient
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/spins:invis:benno/15.4/spins:invis:benno.repo
zypper refresh
zypper install perl-Mail-IMAPClient