Для openSUSE Tumbleweed запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/home:EGDFree:vacuum-im:git:qt5/openSUSE_Tumbleweed/home:EGDFree:vacuum-im:git:qt5.repo
zypper refresh
zypper install vacuum-im-plugins-gmailnotify
Для 15.6 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/home:EGDFree:vacuum-im:git:qt5/15.6/home:EGDFree:vacuum-im:git:qt5.repo
zypper refresh
zypper install vacuum-im-plugins-gmailnotify
Для 15.5 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/home:EGDFree:vacuum-im:git:qt5/15.5/home:EGDFree:vacuum-im:git:qt5.repo
zypper refresh
zypper install vacuum-im-plugins-gmailnotify