Never Spam

If people are not opening your emails, there might be several reasons for that:

1. your content is not good enough
2. your subject line is too “marketingly”
3. your DNS records are wrong (SPF & DKIM)
4. your IP has bad reputations
5. your subscribers are no longer interested (cold subs)
6. your subscribers only subscribed because you mislead them (what they are getting is different from what they expected)

However, you should never spam. Spamming would not only NOT help with your open rate. It will significantly decrease your open rate and email reputation and ultimate do huge damage to your business should your biz rely a lot on email marketing.