If you notice a shift in your inbox placement rate, there may be several reasons.

Campaign behavior

A change to the way you conduct your email campaigns may translate into a change in inbox placement rate. You may look at your:

• Sending frequency. A change in how often your subscribers receive emails can sometimes cause a drop in engagement or a rise in complaints.
  
  
• List management. Using older email lists that are not actively engaged, or not following regular hygiene practices  could mean your subscriber base is stale and could put you at risk of encountering spam traps. Maintaining good hygiene practices may increase your overall engagement rates and deliverability.
  
  
• Campaign strategy.  Customers become familiar with your email program and a new mail stream or a significant change in an existing one can be enough to cause an impact to your deliverability.

Return Path data

With recent policy shifts at major mailbox providers and the addition of SmartSeeds, you may notice changes to the activity included in your subscriber data in Return Path Platform.

• Since the Return Path Seed List now includes SmartSeeds, you could see changes to your metrics. Because SmartSeeds are treated like new subscribers by mailbox providers, engagement metrics can initially be uneven while the mailbox provider learns the behavior patterns each SmartSeed displays. You may see a fluctuation in SmartSeeds data during this time.
  
  
• SmartSeeds are currently available for Gmail, Microsoft, and Yahoo. For other mailbox providers, you have data from CoreSeeds. CoreSeeds represent inbox placement determined at the mailbox provider gateway and derived from the sender reputation, but does not show placement for the differing engagement levels of the SmartSeeds (and, by extension, the real subscribers) you mail to. CoreSeeds will typically skew higher on their inbox placement rates than SmartSeeds because of their limited engagement profile. You can use CoreSeeds to diagnose and react to larger problems at mailbox providers that don't filter on engagement.

Partner Platform handles subscriber data differently, but you may still notice changes to your clients' inbox placement rate.

• Unlike in Return Path Platform, SmartSeeds data in Partner Platform is not weighted. The volume listed for each data point is the actual number surfaced for that data type and date.
  

Other changes

• New filtering policies at the mailbox provider level or business level may have a small effect on your inbox placement.