You can use our shared IP pools or dedicated IPs to send messages to your customers.
Shared IP pool (default)
By default, we add email domains to Customer.io’s shared IP address pool to send emails. We manage and monitor multiple IP pools and remove domains that perform poorly to maintain high deliverability.
Send from transactional IP pool
We also maintain a separate, transactional IP address pool. This pool has even higher standards—stricter bounce and spam thresholds—than our default, shared IP pool. This ensures that your transactional messages achieve the highest deliverability. Only domains used with the transactional service can send emails over this IP pool.
If you have a separate sending domain for your transactional messages, you can request that we add your domain to the transactional IP pool from your email settings. Select Manage Domain and click the Mail Servers tab.
When we add a domain to the transactional pool, you can no longer use it to send campaigns or broadcasts.
Send from dedicated IPs
Sending from a dedicated IP is the only way to take full control over your sending reputation. While we go to great lengths to ensure the health of our shared IP network, there is always the chance that your deliverability could be impacted by the sending habits of other Customer.io accounts.
Benefits of a dedicated IP
One of the main benefits of using a dedicated IP address is that it allows organizations to manage their own IP reputation. This means that they can control how their emails are perceived by email providers and recipients. By sending emails from a dedicated IP address, you can build a positive reputation directly with email providers at the IP level.
A dedicated IP address can also improve email deliverability. This is because the IP address is exclusively used for your email sending, and there is no risk of it being blocklisted due to other senders’ actions. This can increase the likelihood of emails being delivered to recipients’ inboxes, rather than being filtered into the spam folder.
Requirements for sending from a dedicated IP
The only requirement is that you have a minimum volume threshold of at least 50,000 emails per week on the dedicated IP across all of the domains using it. We set this threshold because low email volume can result in unpredictable deliverability performance with inbox providers.
Cost of a dedicated IP
Premium level customers can request up to three dedicated IPs at no extra cost. Outside of that, each dedicated IP is $50 per month.
Request a dedicated IP
To request a dedicated IP for your Customer.io account, first make sure you meet the minimum volume limit. Then go to your email settings and click Manage Domain. Select the Mail Servers tab followed by Dedicated IPs and fill in the form.
We will review your request, sending volume, and any other influencing factors prior to beginning the warming process.
Set up and IP Warming
At Customer.io, we completely handle the setup, warming, and configuration of your dedicated IPs. All that is required from you is to send email normally, and we’ll take care of the rest. Depending on your volume, the warming process can take 30-45+ days. Senders with a higher volume generally move through the warming stages more quickly.
During warming, you will send from your currently assigned, shared IPs as well as your new dedicated IPs. As time progresses, we will slowly increase the amount of email sent via your dedicated IP until warming is complete. When your IP is ready, we’ll shift all sending to your dedicated IP and let you know you’re good to go.