Your emails can land into spam box due to the following reasons:
- Removal of SPF record
- Bad domain or custom envelope reputation
Every recipient server is different and may apply different spam filtering criteria. Recipient servers don’t provide any information about spam filtering to the sender of a filtered email, as it would expose their spam filtering mechanism to the spammers who would use that data to get around spam filters.
Spam filters are constantly changing to adapt to new techniques and types of spam messages, so what lands in the inbox today could be filtered tomorrow. However, there are a few things you can do to ensure inbox delivery of your emails.
Most major email providers, including Gmail, Yahoo!, Hotmail use engagement-based filtering to help detect spam. It means that the more your recipients interact with your emails, the more highly engaged your audience is, and the more likely your emails land in recipients inboxes. The possibility of email landing in spam folders increases when many users are marking your emails as spam. If you succeed in moving your significant chunk of emails out of the spam folder, then it’s a positive sign of getting your future emails delivered in recipients inbox.
Updated about 3 years ago