Technology Overview for Email Delivery
We currently have two dedicated mail servers running a high-end, high-performance Mail Transfer Agent (MTA). We have split 30 IP addresses across both of these MTAs and have groups of them dedicated to certain purposes and clients.
With this configuration we are able to achieve maximum throughput for each of our clients. We are able to send well over 2.5 million emails per hour out of these systems, but recommend sending in the 1 million per hour range in order to be compliant with all major ISPs sending regulations. We typically send between 1.5 and 2 million email messages per day across all our nodes, ramping up to over 4 million on a day where our largest client sends out a full list email blast.
We handle all bounce backs and unsubscribe/abuse complaints in near real-time in order to keep the highest reputation of all our IP addresses to ensure maximum deliverability for all our clients. In order to do this, we have established relationships with all the major ISPs to ensure that we are following their guidelines at all times. The knowledge gained through these relationships as well as our own in-house expertise has allowed us to create a custom sending configuration for all of the major ISPs resulting in maximum speed and deliverability.Through all of our processes we are able to achieve roughly a four percent bounce rate across all IP addresses per day. This is considered very low and is well under the ISP-required five percent bounce rate ceiling. With a well-maintained, clean list these numbers can be driven significantly lower. As a result of our processes and procedures related to the post-processing performed on email blasts, 90 percent or more of these bounces are related to normal account turnover (expiry after 30 days of not logging in) and other failures at the recipient server level.
See also: Bounce Processing
We also monitor large email blasts in real-time using a "eyes-on" approach to best be aware of any issues as they happen. If an issue does come up during a blast, immediate action is taken to resolve the problem in the shortest amount of time possible. When a long delay is required between problem discovery and resolution, a variety of actions can be taken to hold onto the messages before they are released again after the issue is resolved.
What is SPF?
The Sender Policy Framework (SPF) is a record that is created in your Domain Name System (DNS) that a mail server can check against to verify that the email is coming from an approved mail server for that domain. It is essentially a guarantee that the e-mail is coming from where it says it's coming from.
Learn more about SPF at http://www.openspf.org/Introduction.
Create an SPF Record
- Log into your DNS
- Create a new txt record
- In the IP address field, enter
v=spf1 mx include:salsalabs.net ~all
- Leave the host field blank