There is certain things you can do to reduce the risk of being caught in spam filters. Adjusting the way you write and display the content of the newsletter will help hugely.
Tip 1.
Try to be a bit clever with your newsletter subject.
"Free gift with all sex toys this weekend" is going to go straight into the depths of the spam folder without any thought as you have two highly weighted spam words. "FREE" AND "SEX TOYS" both score very high in spam word analysis (the fewer points, the less likely an email is Spam). For example it would be better to use "complimentary toy" and "Marital Aids"
Tip 2.
Subscription Options.
Offer directions for "subscribing" and "unsubscribing." In some Spam filters, you actually lose points (the fewer points, the less likely an email is Spam) when you offer subscribing and unsubscribing instructions.
Tip 3.
Credibility.
Send it from a reputable domain name, or better yet, your own shop domain. Free email addresses are often used heavily by Spammers, so you'll want to stay away from them if at all possible.
Tip 4.
HTML code issues and our Free Hide URL Service.
Spam filters not only check the text of the email for spam words but will also pick up on HTML. If you are making a HTML newsletter that's contains images and links and your domain is adult related with a highly weighted spam word within the URL you are fighting a losing battle against the filters.
Let's say your Website URL is www.sextoys-xyz.com then your HTML code will contain links to your home page with "sex" in the URL. Immediately your newsletter will be spam filtered.
There is a solution to this and it is to use a Free Hide URL Service.
You can use ShortURL service here: ShortURL