Since AcyMailing 3.7.0, we included in all our paid versions a spam test so you can easily test your Newsletter against spam filters (SpamAssassin), check your server configuration and malformed content.
When you preview a newsletter, you will see a button named "Spam Test" in the top right corner of the window. Click it to start the test.
AcyMailing will send an e-mail from your server and check it.
If this is the first time you run a test for this newsletter, you will be asked to wait a few seconds in order for your mail to be processed.
Once your newsletter is processed, you should be able to see the following page with your score.
Clicking on a test title will give you details.