Why are Sailthru emails sending through shared IPs despite having dedicated IPs, according to SparkPost?
Summary
What email marketers say10Marketer opinions
Marketer from Email Geeks asks if Karoline is doing an IP warm up and using the automated process that directs overflow volume to the shared IP pool.
Email marketer from Email On Acid suggests it could be due to a routing issue where Sailthru is configured to send certain types of emails (e.g., transactional emails or emails to less engaged users) through shared IPs to protect the reputation of dedicated IPs.
Email marketer from Litmus shares Email testing tools can sometimes misattribute sending IPs, leading to inaccurate reports of shared IPs being used when dedicated IPs are actually in place.
Email marketer from Quora shares that it may be a configuration issue within Sailthru's settings, possibly related to fallback options or routing rules that need adjustment.
Email marketer from Mailgun forums shares that Reporting inaccuracies can occur in platforms like SparkPost due to how they track IP addresses and email routes, which doesn't always reflect the final sending IP.
Marketer from Email Geeks explains that the issue is a reporting issue within SparkPost's platform. The platform is picking up the internal filtering IPs and not the external IP that the mail is actually being sent out on. He has opened up a ticket with their engineering team to resolve it, and confirmed emails are going out on the dedicated IP.
Email marketer from Validity explains that there may be misconfigurations within the DNS settings of the sender domain that could lead to emails being routed through shared IPs instead of dedicated ones. This often involves SPF or DKIM record issues.
Email marketer from Reddit explains that shared IPs can sometimes be used for transactional emails or when dedicated IPs reach sending limits, even with dedicated IPs set up.
Email marketer from StackOverflow user responds that multi-tenancy of shared platforms can lead to unexpected routing through shared IPs due to system architecture and resource allocation.
Email marketer from Email Geeks Forum that it might be due to volume thresholds set within Sailthru, where lower volume emails are automatically routed through shared IPs.
What the experts say2Expert opinions
Expert from Spam Resource explains that configuration or coding errors with a 3rd party ESP can cause the wrong sending IP to be used. If the message isn't properly associated with the dedicated sending IP, it may be accidentally sent from a shared IP pool.
Expert from Word to the Wise, Laura Atkins, shares that sometimes email platforms utilize shared IPs for specific types of emails (like transactional or automated messages) even when dedicated IPs are present, based on volume, reputation, or deliverability strategies.
What the documentation says5Technical articles
Documentation from Amazon SES highlights that fallback configurations in email platforms can result in emails being sent via shared IPs if dedicated IPs experience issues or exceed sending limits.
Documentation from Google Postmaster Tools shares that negative IP reputation can lead to emails being sent through shared IPs as a protective measure to prevent deliverability issues on dedicated IPs.
Documentation from SparkPost explains that IP reporting discrepancies can occur if internal filtering IPs are mistakenly identified instead of the actual sending IPs.
Documentation from Sailthru explains that during IP warmup, Sailthru may use shared IPs to ensure deliverability while the dedicated IPs are being ramped up.
Documentation from SendGrid notes that shared IP pools are sometimes used for low-volume or less critical emails, even when dedicated IPs are present, to distribute risk and ensure overall deliverability.