[xwiki-users] Configuring SMTP Server in core files

Hello, Is there a way to configure SMTP Server (for email notifications) in xwiki.cfg or xwiki.properties (or any core files) instead of in the XWiki.XWikiPreferences page ? Indeed, like I use a farm, I'd prefer to set up it once and not in all wikis. I know that I can use wiki template to make it easier but I'd prefer to set up SMTP Server only once and not to use a "trick". Do you know if it's possible ? Thanks, Marine