Admin has started failing to update order status

[bigbob2]

I'm running a healthy v2.3.4 site, which in the last couple of weeks has started to develop an issue.  about 40% of the time, when we update the customer status, it comes up with a red X to show that the customer has not been notified, despite the fact that we always leave that option selected.  Sometimes you can try 2 or 3 times before it does notify the customer and occasionally it just deletes the order entirely when you try to update the status.  I have been using OSC for many many years without any issues, so I would love some ideas on what I could test, try or change to fix this frustrating and potentially dangerous issue.

 

Thanks

Kev

[♥John W]

If you haven't changed anything then it may be something on the server level.  Check with your webhost to see if something has been deployed on the lines of blocking automated emails from webscripts.  Hopefully, your host is good and you can give them a good timeline.  Another site on the server may have been sending spam through scripts which caused them to make changes.  It certainly won't hurt to check this.  

[MrPhil]

Also check if your host recently updated anything, such as moving to a new PHP version. While osC 2.3.4 is still pretty much up-to-date, not all your add-ons may be, and possibly your host just went to PHP 5.6 or 7, and something in the code has broken.