The newsletter filter detects messages that are not pure spam, but by many still regarded as junk or less important. This may include advertising, promotions, information and newsletters from the company you purchased from. However, order confirmations, invoices and bank statements should not be stopped by this filter. If this happens, you let SpamDrain know that it was a "Valid email" or "Ok email" and that it was not a newsletter when you release it from your Blocked list.
When this is turned on, SpamDrain will thus block more types of email. When you release an email that you do not want SpamDrain to block, SpamDrain will make sure not to block similar emails again. Emails that are blocked by this filter will also be listed in your SpamDrain report email. So you do not need to worry about missing important emails from companies you trust. Just keep an extra eye in your Blocked message list the first weeks.
To turn off the newsletter filter log on to spamdrain.com/app.html#settings. Click EDIT in the Your settings box. Uncheck the box Enable Newsletter and marketing filter and click Save. You can also do this through the iOS app under Settings and in the Android app under the the Account tab.