Your delivery rate can be slowed down at several points: by your email service provider, by recipient servers, or by spam filters. Throttling delays your campaigns and your transactional messages, and it is usually a signal that something about your sending needs attention
Throttling between your system and ours
Elastic Email is an all-in-one email delivery platform. We offer an SMTP Relay and a REST API as well as the user interface for submitting emails. If you connect and send through the SMTP Relay or the REST API, take into account the time it takes to submit all of your emails to the Elastic Email network.
We limit each user to 20 concurrent connections for both SMTP and API. This makes sure that no single user can dominate the submission servers. We also recommend setting any connection timeout to at least 30 seconds
Elastic Email System Throttling
Have you ever encountered a warning on your account stating that your email delivery is being throttled?
We continuously monitor all outbound traffic from our servers and analyze the feedback from the destination servers that process your emails. If they ask us to slow down, we comply. If they ask us to stop, we suspend the delivery.
Your reputation as a sender, and our reputation as your provider, both depend on how those destination servers see your emails. A throttling warning on your account means that external servers currently view your emails unfavorably.
Recipient Server Throttling
If many of your emails are stuck in the "In Progress" queue with a "Waiting to Retry" status, or are bouncing with a "Throttled" or "Not Delivered" status, recipient servers are most likely throttling your delivery rate. They can handle this in several ways: they may accept the connection but greylist the email, or they may defer the connection entirely.
If this happens consistently, there is usually an ongoing issue with your emails that needs to be addressed. Content quality, the sending IP, and domain reputation are the first things worth checking.
What causes my email to be throttled?
Elastic Email and the recipient servers tend to throttle for the same reasons. If recipient servers throttle your email, then likely the Elastic Email system will do it too. Here are the most common reasons why your email is being throttled:
Abuse Reports
This is the easiest way to get throttled. Elastic Email has a very low tolerance for Abuse Reports and so do recipient servers. If your contacts complain/report your email then your email may become throttled and may not be delivered. You will get abuse reports if your email is unsolicited, not double opt-in or does not have a working unsubscribe link.Sending to invalid email addresses, or old email addresses
If you send to old, inactive addresses, even ones that signed up for your service at some point, those addresses may now be spam traps. This can get our IPs blacklisted and will lead to throttling of your mail. Do not send to addresses you have not emailed for more than a year, and treat six months as the safer limit..Sending poorly formed content
Make sure you run your content through a spam checker before you send it. This is particularly important if you are in an industry which is generally associated with high spam volumes such as Mortgage Lending/Real Estate, Gaming and similar, or Affiliate Marketing.
How we define spam
In general, unsolicited email that is not double opt-in will likely become throttled and will not get delivered. We use the Spamhaus definition of spam, which you can read at https://www.spamhaus.org/faqs/general-definitions/#what-is-the-definition-of-spam.
If you keep sending unsolicited email and your delivery is throttled continuously as a result, Elastic Email may not be the right fit for your sending, and you may need to look for another email provider or set up your own email delivery servers.
How long we keep trying to deliver
The Elastic Email system attempts to deliver your email for up to 48 hours. If we cannot deliver it within that time, the message is removed from the queue. If the system determines before the 48 hours are up that the message cannot be delivered at all, it is removed earlier.
There is no refund for undelivered mail. See our Terms of Use at http://elasticemail.com/terms, where we cover using our system at your own risk.
Getting back to normal sending
Many users who run into throttling are not aware they have done anything wrong, and a throttled account is not a permanent state. If you have started fresh with a list of contacts who explicitly asked for your emails, removed old and inactive addresses, added a prominent unsubscribe link, and checked your content for spam triggers, you are ready to send again.
You can simply start sending. Our system is highly responsive and your emails will begin to flow right away. The throttle warning may stay at the top of your screen for a while, but as long as your emails are being delivered promptly, you are on the right track. After you have successfully sent at least 10,000 emails without abuse reports or excessive bounces, the throttle warning may disappear, which confirms that your account has been moved out of the risky pool.
If you are confident that your emails and your contact lists meet the highest standards but you are still being throttled, contact our support team so we can look into it.