If you’re landing here, chances are you run a Sendy instance on Amazon EC2 hosting “Simple Email Service (SES)” for email marketing and experience the following problem:
- Error 1: “View All Lists” Not Working/Loading
- Error 2: “Send Newsletter Now!” Not Working/Loading (Recipients loads forever)
Here’s a screenshot on my Sendy instance — the lists don’t load!
How to Fix?
To fix these two errors, you simply need a bigger Amazon EC2 instance in all likelihood. Per default, Sendy installs the Amazon t2.micro instance that has only 1 GiB of memory.
For large lists, however, this is not enough. The instance is likely overwhelmed with all the list data if you have, say, 100k+ subscribers. To overcome the small memory, the instance needs to store parts of the “memory data” (i.e., the list) on stable storage, which reduces performance by orders of magnitude. Hence, the timeout on all major browsers.
How to Increase the EC2 Instance Running SES?
To increase the capabilities of your instance and fix this error, just follow these three steps:
- Step 1: Stop the instance at the Amazon EC2 region: https://eu-central-1.console.aws.amazon.com/ec2/home
- Step 2: Wait for the instance to stop and change the instance type from
t2.microtot2.smallto double its memory capabilities. If you need more power later, try to increase it even more. See instance types here. - Step 3: Restart the instance again. And voilà – your Sendy installation should work again!
See here: https://sendy.co/forum/discussion/669/ec2-micro-strong-enough-to-sendy-50k-mails
I hope this worked for you – thanks for checking out this tutorial! 
https://www.sickgaming.net/blog/2023/02/...s-forever/