There are several reasons that may cause your emails to end up in the spam folder.
High Spam Complaint Rate: if your recipients mark your email as spam, email providers start treating your email as untrustworthy. According to a report, a complaint rate above 0.1% can be seen as a threshold by email service providers.
Low Engagement Rates: Email providers monitor how recipients interact with your email. Emails with an open rate below 15% to 20% indicate that your emails aren’t considered valuable and are likely to be flagged as spam.
Poor Email List Quality: Sending emails to inactive or incorrect addresses can hurt your reputation. A bounce rate above 2% signals to your email provider that your email list is either of poor quality or outdated.
Use of Spammy Language: Low-quality marketing messages can trigger spam filters. For example, if your subject line reads, ‘Congratulations, you have won a trip,’ it is likely to be flagged as spam.
Improper Email Authentication: Emails without proper authentication, such as SPF, DKIM, and DMARC, can appear suspicious, making them 10.1 times more likely to be flagged as spam by email providers.