Smartlead’s warmup infrastructure sends 25 million warmup emails daily (as of Feb 24).
The quality of the pool is crucial to ensure your reputation and sending score improves as well as overall domain health.
At times your mailbox can reject emails for a variety of reasons, some of which can be:
Your credit card expired and your mailbox started rejecting emails
Your MX records and DNS settings changed/expired
You have a very strict DMARC policy rejecting emails from certain vendors
Your ESP service is clogged and is rejecting emails temporarily / moved them to a queue state
Your mailbox is full
You have strict filters to prevent external companies from emailing you
You have certain copy filters to prevent emails with trigger words from being approved
To name a few.
When a bounce happens in the warmup network, we will automatically move the mailbox that caused the bounce to a cool-off period. This cool-off period exists to allow for the ESP to adjust itself in case of a:
Network clog
Payment rejection
Mailbox being full
This prevents unwanted bounces from other mailboxes in the warmup pool who are trying to interact with you.
After a safe time gap, through our data we've analyzed this to be 4 hours, Smartlead will send another email to see if messages are being accepted.
If they are, it will add it back to the warmup pool and everything carries on as is, without affecting your reputation or the reputation of the mailbox interacting with you.
In a situation even after 4 hours your mailbox still rejects emails, we'll move it off the warmup pool and you will need to manually verify that it is accepting as well as sending emails in a safe manner by contacting support with proof of screenshots for both scenarios (sending and accepting)
This is an over simplified explanation of the intricacies that go onto determining the time, whether to move a mailbox to cool off or not, but the goal stays consistent - to provide the best dynamic and high-value warmup infrastructure in the world that consistently improves your mailbox reputation