Do my origination and outbound IP addresses need to be the same?

Not necessarily. The origination IP is where the email journey begins (e.g., your computer), while the outbound IP is the last server's IP that delivers the email to the recipient. They are often different, especially when using email service providers or complex network setups.

Why is the outbound IP more important for deliverability?

The outbound IP is critical because it's the IP address that recipient mail servers use to assess your sender reputation. Factors like spam complaints, bounces, and blacklist status are tied to the outbound IP, directly affecting your deliverability.

Should my outbound IP have a PTR record?

Yes, it's highly recommended to have a PTR (reverse DNS) record for your outbound IP. Many mailbox providers require this to verify the legitimacy of the sending server. Without it, your emails might be rejected or sent to spam.

What if my outbound IP changes unexpectedly?

Yes, if your outbound IP changes due to network configuration (e.g., firewall NAT), it's crucial to update your DNS records, particularly your SPF record, to include the new IP. A mismatch can lead to emails failing authentication and being rejected.

How do email service providers (ESPs) affect my outbound IP?

Using an email service provider (ESP) typically means your emails are sent from their managed, warmed IP addresses, improving deliverability. They handle the complex task of maintaining good IP reputation across various mailbox providers.

Should my origination IP and outbound IP be the same when sending email? - Technical - Email deliverability - Knowledge base

One of the questions that comes up often when talking about email deliverability and infrastructure is whether your origination IP address and your outbound IP address should be the same. It is a common point of confusion for many sending emails, whether directly or through a third-party service.

The short answer is: they don't have to be, and often they are not. The distinction between these two IP addresses is crucial for understanding how email flows and how deliverability is affected. Let's break down what each means and why their relationship matters.

Understanding the distinction between origination and outbound IPs

When an email is sent, it typically passes through several servers before reaching its final destination. Each server along this path adds a Received header to the email's metadata. These headers document the journey of the email, including the IP addresses of the servers it traversed.

The origination IP, often found in headers like X-Originating-IP, refers to the IP address of the very first machine that initiated the email. This could be your local computer's IP if you're sending directly from an email client, or an IP address associated with a webmail service (like

Gmail). It essentially marks the starting point of the email's journey. Learn more about the X-Originating-IP header.

The outbound IP, on the other hand, is the IP address of the mail server that actually sends the email to the recipient's mail exchange (MX) server. This is the IP address that recipient mail servers see as the sender's identity. In many common setups, particularly when using an Email Service Provider (ESP) or a large mail relay, the outbound IP will be different from the origination IP.

The importance of the outbound IP for sender reputation

From a deliverability perspective, the outbound IP address is far more critical than the origination IP. Recipient mail servers primarily evaluate the reputation of the outbound IP to determine whether to accept, quarantine, or reject incoming email. This reputation is built on factors like sending volume, spam complaints, bounce rates, and whether the IP is listed on any email blacklists (or blocklists).

A key factor for the outbound IP's reputation is its PTR record (pointer record), also known as reverse DNS. This record maps an IP address back to a hostname. Most major inbox providers, including

Google and

Yahoo, require that the public IP address of a sending SMTP server has a corresponding PTR record that resolves to a hostname. This check helps verify that the sending server is legitimate and not a rogue actor.

If the outbound IP address is on a blacklist, it can significantly impact your email deliverability, regardless of the origination IP. This is why blocklist monitoring is so important. Consistent positive sending behavior from the outbound IP is essential for maintaining a good sender reputation and ensuring your emails reach the inbox.

When IPs are the same

Direct sending: If you host your own mail server and send emails directly from it without any intermediary relays or firewalls performing network address translation (NAT), then your origination IP and outbound IP would indeed be the same. This setup is common for smaller organizations or personal mail servers.
Simpler setup: Having the same IP can simplify DNS records, such as SPF or PTR records, as you only need to manage one public IP for email.

When IPs are different

Email service providers (ESPs): When you send emails via an ESP like SendGrid, Mailgun, or Amazon SES, your origination IP is the IP of the machine making the API call to their service. The outbound IP will be one of the ESP's sending IPs, which they manage and warm for optimal deliverability. This is a very common and recommended setup for most senders.
Network configurations: Organizations often use firewalls or NAT devices that translate internal private IP addresses to a single, or a pool of, public IP addresses for outbound internet traffic. In such cases, your internal mail server's IP (origination) will differ from the public IP used for sending (outbound). This is standard network practice for security and IP conservation.
Email gateways/proxies: Some companies route all outbound email through an email gateway or security appliance. This gateway then becomes the outbound IP, further abstracting the original sending machine's IP.

Practical implications and considerations

For most businesses, particularly those sending marketing or transactional emails in volume, it's generally better to have a distinct outbound IP managed by a reputable ESP. This allows the ESP to handle the complexities of IP warming, reputation management, and adherence to sender guidelines set by major mailbox providers. ESPs ensure that the IP addresses used for sending are not dynamic, which can lead to email rejections.

However, it's also important to configure your DNS records correctly, including SPF, DKIM, and DMARC, to properly authorize your outbound sending IPs. This tells recipient servers that your ESP is permitted to send emails on behalf of your domain, helping to prevent spoofing and improve deliverability. You can use our free DMARC record generator.

A common scenario where an organization might encounter issues is when they route emails through a firewall that performs NAT, causing the outbound IP to differ unexpectedly from the one configured in DNS records. This mismatch can lead to deliverability problems, as recipient servers may see an unauthorized IP. It's crucial to ensure that any network device that modifies the source IP of outgoing email is properly accounted for in your SPF records.

Example email headerstext

Received: from mail.yourdomain.com (mail.yourdomain.com [192.168.1.100])
        by outbound-relay.esp.com (outbound-relay.esp.com [203.0.113.42]) with ESMTP id ABCDEF12345;
        Wed, 10 Nov 2023 10:00:00 -0500
X-Originating-IP: [198.51.100.1]

Troubleshooting deliverability issues with IPs

If you're experiencing soft bounces or rate limiting from mailbox providers like rr.com, it can indeed be frustrating, especially if your sending volume hasn't changed. While an origination IP mismatch is unlikely to be the primary cause, a change in your outbound IP's reputation certainly could be. This is why consistent monitoring of your sender reputation is vital.

Mailbox providers might implement rate limits or temporary blocks if they detect unusual sending patterns, an increase in spam complaints, or if your outbound IP gets listed on a blacklist or blocklist. Even with a good list and high engagement, if your IP reputation dips, deliverability can suffer. Regular blocklist checks are part of maintaining healthy email sending.

Sometimes, issues can be with the recipient domain's infrastructure. Older email providers, such as certain regional ISPs, might have less sophisticated systems that are prone to intermittent issues or overly aggressive filtering. In such cases, while your sender practices are solid, the recipient's system might be causing the temporary block.

Views from the trenches

Best practices

Maintain a consistent sending volume and pattern from your outbound IP.

Regularly monitor your outbound IP's reputation and check for blacklistings (blocklistings).

Ensure your DNS records (SPF, DKIM, DMARC) are correctly configured and aligned with your outbound IP.

Use an Email Service Provider (ESP) for high-volume sending to leverage their managed IP infrastructure.

Common pitfalls

Not having a proper PTR record (reverse DNS) for your outbound IP address.

Changes in network configuration (e.g., NAT, new firewall) that alter your outbound IP without updating DNS records.

Ignoring soft bounces or rate limiting messages, which can indicate underlying reputation issues.

Sending from dynamic IP addresses, which are often classified as problematic by recipient mail servers.

Expert tips

If your volume hasn't changed but you're getting rate limited, your IP reputation might have declined.

Focus on the outbound IP's reputation, as it's what recipient servers primarily assess.

Even with high open rates, temporary blocks can occur if mailbox providers perceive an issue with the sending IP.

Ensure your DNS records authorize the IP address actually sending your emails.

Expert view

Expert from Email Geeks says they don't have to be the same and often aren't, explaining that originating IP is where the email initiated and outbound IP is what sent it to the recipient's server.

2020-11-10 - Email Geeks

Marketer view

Marketer from Email Geeks says they compose messages outside their ESP and push via API, but recently saw soft bounces and are looking for causes.

2020-11-10 - Email Geeks

Key takeaways for IP management and deliverability

While it's not a requirement for your origination IP and outbound IP to be identical, understanding the role of each is vital for effective email deliverability. The outbound IP is the one that carries your sending reputation and is scrutinized by recipient mail servers.

Whether your IPs are the same or different largely depends on your sending infrastructure. For most organizations, especially those using ESPs, having distinct IPs is normal and often beneficial for managing reputation and achieving high inbox placement rates. The key is to ensure that your outbound IP is authorized and maintains a solid reputation. Ensuring your email authentication protocols like SPF, DKIM, and DMARC are correctly implemented for your outbound IP is paramount.