By default, SPIP 4.3 sends an email to all site webmasters when a SPIP update is available.
Topic: [SPIP-Contrib] SPIP upgrade 4.3.0 is available
Hello,
The site https://contrib.spip.net can be upgraded to the newest SPIP version.
To avoid security problems, it is important to keep your site up to date.
The constant _MAJ_NOTIF_EMAILS allows you to customise the list of addresses to which these emails will be sent. It can be customised in your config/mes_options.php file (see the article dedicated to it).
For example, if you want to disable these notifications (which is not a good idea):
// disable update notifications
define('_MAJ_NOTIF_EMAILS', '');