Install your wanted mail client in
/var/lib/
Make sure www-data has read access
Create templates in:
Depending on your setup:
for mailclient.tpl and stpl
default_mailclient.tpl and stpl
or for “nginx only”
https://github.com/hestiacp/hestiacp/blob/main/install/deb/templates/mail/nginx/mailclient.tpl and stpl
Modify /usr/local/hestia/conf/hestia.conf line:
WEBMAIL_SYSTEM=‘roundcube,rainloop’
to WEBMAIL_SYSTEM=‘roundcube,rainloop,mailclient’