Should my origination IP and outbound IP be the same when sending email?
Summary
What email marketers say9Marketer opinions
Email marketer from SendGrid explains that with dedicated IPs, the outbound IP is typically managed by SendGrid. Your application connects to SendGrid from an origination IP, but SendGrid handles the sending from its own infrastructure using the dedicated IP you've configured.
Email marketer from Litmus explains that when using a third-party email service, your outbound IP reputation is managed by them. This is separate from your origination IP. They recommend regularly monitoring your deliverability.
Email marketer from Email on Acid explains that the IP reputation of the outbound IP address is what email providers look at. The origination IP is not relevant. They suggest warming up dedicated IPs to protect sender reputation.
Email marketer from Reddit answers if you're running your own mail server at home, your origination and outbound IP will likely be the same because your server is both initiating and sending the email. However, this setup is not recommended for production environments due to deliverability issues.
Email marketer from Omnisend explains that your sending and origination email IP address can be different. When connecting to your email service provider you will have a different IP address that the sending server uses to deliver its email. They recommend using a dedicated IP for its customer to improve email outcomes.
Email marketer from SparkPost mentions that if you are using a dedicated IP for sending, SparkPost manages the outbound IP reputation. The origination IP is only used for connecting to their service, not for direct email sending.
Email marketer from StackOverflow answers when using the PHP mail() function directly, the origination and outbound IP might be the same if your web server is also configured to send emails directly. However, this is generally discouraged for production environments due to poor deliverability.
Email marketer from GMass explains that the email origination and outbound IPs are typically different. In this case GMass provides IPs for its customers to use to send emails so that individual IP addresses don't get marked for poor email practices. This improves email deliverability rates.
Email marketer from Mailjet Blog explains that the origination and outbound IPs don't necessarily need to be the same, especially when using a dedicated email service provider (ESP). The origination IP might be where you initiate the email sending process, while the outbound IP is the one used by the ESP to actually send the email.
What the experts say4Expert opinions
Expert from Spam Resource explains that in a cloud-based sending infrastructure where multiple IPs are used for sending email, your origination IP would be that of your application server, while the outbound IP would be one of those used by the cloud provider. The cloud provider manages the sending reputation so the outbound IP being the same as the orginating is not required.
Expert from Email Geeks explains that originating IP and outbound IP don't have to be the same and often aren't. Originating IP is the IP of the machine that initiated the email, while outbound IP is the IP that actually sent the mail to the recipient’s MX.
Expert from Word to the Wise explains that it is beneficial to have distinct mail streams for different purposes (transactional, marketing, etc.) and these can originate from different IPs. Therefore, the origination and outbound IPs would not necessarily be the same.
Expert from Email Geeks suggests that if RR.com is actively rate limiting and the volume hasn’t changed, it’s possible the sender's reputation has decreased, causing them to slow down the mail.
What the documentation says4Technical articles
Documentation from Microsoft explains that SPF records authorize sending mail servers. The outbound IP needs to be included in your SPF record, but your origination IP (where you connect to your ESP) doesn't.
Documentation from Amazon Web Services explains that with Amazon Simple Email Service (SES), you don't manage outbound IPs directly. AWS SES uses a pool of IP addresses to send emails. Your origination IP (where you connect to SES) is separate from the outbound IPs used by SES.
Email marketer from Digital Ocean explains that when you run your own email server you will have an IP address associated with your server. This IP address is both your originating and sending IP. It recommends that you properly configure your DNS records such as SPF, DKIM and DMARC records in order to improve your reputation for sending email.
Documentation from RFC Editor explains that the SMTP protocol involves a client connecting from an originating IP address to a mail server. The mail server then sends the email from its outbound IP. These IPs can be, and often are, different.