I believe your site user will not see this error is because only site admin can able to send message to everyone on the site.

Based on what i checked, it seems like your site total of user is around 1.7k, it might need more PHP memory_limit to handle this.

Perhaps you can try increase your PHP memory_limit to 512M and see if you still hitting this error.

Hi Arlex,

yes admin, she is our client but admin user.

How do I increase this to stop any errors like this happening again? We are expecting to eventually have 12k members, what are your suggestions?

Thanks
Katie

You can request with your webhosting provider to assist you increase this PHP memory_limit from your PHP server, because different server php.ini file is located at different location.

We are expecting to eventually have 12k members, what are your suggestions?

Currently I haven't try to send 1 message to 12k member yet, but i believe as long as your PHP memory_limit and max_execution_time set to higher, then it should be fine.

memory_limit = 1064M
max_execution_time = 1000