The spam folder is the storage space in your email account for unwanted emails or for emails that fail to reach your inbox and are flagged as spam by email service providers (ESPs). It is also known as the "Bulk Folder" or "Junk Folder".
These filtering systems are created to help users decrease the amount of unnecessary and promotional emails that they receive.
When you send a message, email service providers (ESPs) look at your email address' reputation and the content of the email message. If there are any aspects that appear suspicious, ESPs automatically block your email from reaching the targeted inbox. Receivers are also able to flag an email as spam.
Sign in to your Gmail account
Under the "Categories" section, click on "More".
There may be email spam filter issues
Sender's email may have a low sender score
The IP adress may not be reputable.
Domain authentication requirements may be neglected.
The domain may not be reputable.
The sender may not have obtained customers' permission.
The email sending frequency of sender may not be set.
The sender may have low email open rates.
The email list of sender might not be up to date.
There may be no unsubscribe links.
Sender information could be incorrect.
The content of the message may include spelling mistakes and grammatical errors.