Subject and content of an email are important in maintaining your reputation in Gmail spam filters. The message that Gmail displays when an email has triggered the spam filter is shown below:

This might be due to one or more of the following issues:

• Usage of certain words in your content/subject such as buy, order, discount, clearance, dear friend, as seen on, please help, free, offer, desperate, additional income, etc may result in marking of spam. These words may raise suspicion either to your email recipi or Gmail. It is strongly recommended to avoid usage of spam triggering words in both subject and email content.
  
• The subject may not convey the message you actually intended to deliver to your subscribers. Due to this, your subscribers may get mislead and mark you as spam. Ensure that your subject and content are relevant to each other.
  
• Sometimes usage of a genuine word at a wrong time may result in being marked as spam. Some words become spam triggering during certain seasons. For example, when a hurricane hits a province, words like help, disaster recovery, fundraising, etc will become spam triggering. Once the hype created by the hurricane ends, these words will get less spam triggering.
  
• Seeking sensitive information in the content of the email itself or in a landing page redirected from your email campaign creates suspicion among subscribers. If it is necessary to collect sensitive information, then add an optional step to ask such details while your subscribers sign up.
  
• Announcements via email need to be crisp, as a lengthy piece of content will bother your subscribers due to the inconvenience to read. The general ideal size for a subject is up to 4-6 words. Be a strict judge and choose words which are necessary.
  
• Typos (spelling mistakes) can reduce reputation among subscribers and Gmail. Check for typos in your subject as well as content before you hit the send button.
  
• Ensure that the URLs you add in your content are neither blacklisted nor of lower reputation, and avoid secondary domains and multiple redirecting links.
  

The reputation of your domain may get reduced due to any of the above scenarios. There are some suggestions from our deliverability team to consider while you craft your email subject and content:

• Request your subscribers to add your sender address to their contacts, so that your emails have high chance to land in inbox, especially in the Primary Tab.
  
• Highlight the unsubscribe link clearly.
  
• Avoid bright colors, such as red, as background colors in your email.
  
• Include images in your email, but make sure you add textual content as well (in case your images fail to load). A proper image-text ratio gives more reach to your campaign.
  
• Avoid ALL CAPS, links, and irrelevant punctuation in your subject or your emails may land in spam.