安装virtualmin后，opendkim安装（apt install opendkim opendkim-tools）失败，如下所示：
Do you want to continue? [Y/n]
Setting up opendkim (2.11.0~alpha-11build1) ...
Job for opendkim.service failed because a timeout was exceeded.
See "systemctl status opendkim.service" and "journalctl -xe" for details.
invoke-rc.d: initscript opendkim, action "start" failed.
● opendkim.service - OpenDKIM DomainKeys Identified Mail (DKIM) Milter
Loaded: loaded (/lib/systemd/system/opendkim.service; enabled; vendor preset: enabled)
Active: activating (auto-restart) (Result: timeout) since Sun 2020-08-02 09:45:05 EEST; 9ms ago
Docs: man:opendkim(8)
man:opendkim.conf(5)
man:opendkim-genkey(8)
man:opendkim-genzone(8)
man:opendkim-testadsp(8)
man:opendkim-testkey
http://www.opendkim.org/docs.html
dpkg: error processing package opendkim (--configure):
installed opendkim package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
opendkim
E: Sub-process /usr/bin/dpkg returned an error code (1)