as I have learned, mass mailing via the build-in tool in oxwall/skadate relies on the cron job. The problem here is, that if you have lots of users, your website will crash since the cron can´t handle many users. 

I am trying to send a mass email to a few thousand users and cannot find a tool, that does not rely on the cron job. I have tried the oxwal tool and mailjet plugin available in this store. 

Same issue: both of them crash the website and only send a few newsletters. 

Does anyone have a solution for this? It obviously should still work with the basic newsletter features like "unsubscribe", "pictures", "Links" etc. 

Thank you for your help!