Xibo Email Alert: Display is Online again - comes multiple times

we use Xibo 1.7.9.
When a display is offline, I get one email. Done.
Wehn it goes online again, I get the email “… is online again” multiple times. ~25 mails arrived me! With the exact content.
Whats wrong here? Any hint?
The cronjob is configured like this:

## Run Xibo cronjob
*/10 * * * *    root    cd /var/www/xibo.jki.bund.de && php maintenance.php changeme

It was resolved in 1.8.0-rc1 - Duplicate display down emails · Issue #925 · xibosignage/xibo · GitHub

As for 1.7 series, are you using player collection interval or global timeout?
Perhaps have a look at email alerts section of this guide

The reason this happens is you effectively have a race condition.

When the Player comes back online, it makes multiple simultaneous connections to the web service asking for new content. As it does so, the “up” email is triggered, and then a flag is reset in the database to say that the display is back online.

Unfortunately, as many connections come in at the same time, only ones that happen after that flag is reset will then not generate an email. As Peter says, it’s been rectified in 1.8 series so it will be fixed going forward.