Yahoo Mail’s Storage Limit Change Impacts Senders

Yahoo Mail’s Storage Limit Change Impacts Senders

Senders have always had to develop strategies around how to handle recurring blocks. One of the main reasons for recurring blocks is mailbox/ storage full. In the past, if we started seeing ‘mailbox full’ blocks for a subscriber - it was highly likely that the subscriber was not active and just let their mailbox become full. 

In recent years, that line of thinking has shifted somewhat. We now see that roughly 8.5% of addresses that show ‘mailbox full’ over a 30 day period go back to the active state and start seeing deliveries again. Some Mailbox Providers have reduced or altered storage limits over the years, which results in higher block rates due to mailboxes/ storage being full. On top of that, storage isn’t just tied to email in some cases. Photos, documents, etc can result in storage becoming full. Yahoo Mail recently announced a reduction to 20GB of free storage.

This is very much in line with the other major Mailbox Providers, although a significant drop from the previous 1TB storage limit Yahoo Mail had. Yahoo Mail customers do have options to upgrade to plans with 100GB or 1TB storage limits. 

What’s the Impact?

If you are sending to highly engaged recipients and you have a strict sunset policy, you likely will see very little impact. For senders that have relaxed sunset policies or send re-engagement campaigns, you will likely see an increase in blocks due to mailboxes being full. Below is an example of Yahoo Mail ‘mailbox full’ blocks increasing for one sender as soon as storage limits changed:

When we look at system-wide numbers for Twilio SendGrid, we see a fairly significant increase in blocks due to mailboxes being full for Yahoo Mail over the past few weeks. Since the limit change went into effect, we have seen 5,500% more ‘mailbox full’ blocks from Yahoo Mail. 

Block Codes

Senders should be on the lookout for an increase in block rates with these block/ error codes:

552 5.2.2 This message could not be delivered because the recipient's mailbox is full. Please try again later or contact the recipient directly. See https://senders.yahooinc.com/smtp-error-codes#mailbox-full for more information

552 2 Requested mail action aborted, mailbox is over quota

What Should Senders Do?

If you do notice an uptick in blocks due to mailbox/ storage being full, this would be a good time to review your sunset policy. At what point do you stop sending to subscribers that no longer engage with your email program? Frequency reduction models and sunset policies are some of the strategies our Professional Services team utilize to help companies improve their email program. 

If you are trying to find the optimal sending frequency for your email program, or you are looking to implement or revise a sunset policy, our professional services team is here to assist.