Why are emails not getting immediately sent?
Most of Prefinery customers like you are launching something new, under a new sender address domain, and that domain has not had much email delivery activity, so we need to warm it up.
To help you establish a good sender reputation, sending starts with a lighter frequency and ramp up over time as a pattern of safe and wanted emails is established. This warm-up phase is critical as it signals to ISPs that you are a legitimate source of email traffic, not a source of spam or brute attack.
Prevent soft bounces
Providers like Gmail in particular will soft bounce emails if there was a sudden, huge spike in sending volume for a particular domain. Gmail sees all these emails at once, which is out of the ordinary, and starts to delay delivery and eventually reject the message.
ℹ️ A soft bounce is considered a transient bounce, where something is happening at the moment to prevent delivery (like a spike in sending), and future sends will still be okay to that address. Other examples would be a DNS issue or a mailbox full.
With that, the solution has been to space out delivery through throttling.
Throttling rate
Currently, this is the throttling Prefinery is doing:
- 1,000 emails per hour for the first 5,000 total emails sent
- 5,000 emails per hour for the next 15,000 total emails sent
- 10,000 emails per hour for the next 30,000 total emails sent
- 15,000 emails per hour for the next 50,000 total emails sent
- 20,000 emails per hour for more than 100,000 total emails sent
So, if a customer has 10,000 emails being throttled, it would take 6 hours for all emails to be sent.