Interface setting > mail > max backup copies
Regarding this commit, which enabled to retain up to 30 backup copies (previously limited to 10): aa1eed46
The goal of this merge request is to add an interface setting in order to limit (below 30) the maximum backup copies (for email only), so clients' options would be globally limited when accessing the "Backup" tab.
Before going any further, my guess is to add an interface setting.
And obviously enforce the limit in the
mail_user.backup_copies SQL column when this setting is changed. This could be done using some feature such as the setting input "custom" validator, for example: https://git.ispconfig.org/ispconfig/ispconfig3/-/blob/develop/interface/web/admin/form/system_config.tform.php#L224
For this last point especially, I am not sure this is the way to go, comments are welcome!