Do new domains on shared IPs need warming for transactional emails?

Key findings

• Shared IP warmth: Shared IP addresses are usually already warmed and maintained by the email service provider, meaning you typically do not need to warm the IP itself. OneSignal clarifies that IP warm-up isn't always necessary unless you are getting dedicated IPs.
• Domain reputation is distinct: Your domain has its own independent reputation, which is built on sending behavior, recipient engagement, and compliance over time. A new domain starts with a neutral reputation.
• New domains need warming: Even on a warmed shared IP, a new domain requires a period of gradual sending to build trust with internet service providers (ISPs).
• Volume is critical: High sending volumes from a brand new domain, even for transactional emails, can trigger spam filters and lead to blocklisting. This is because ISPs perceive sudden high volume from an unknown domain as suspicious.
• Transactional email nuance: While transactional emails are generally highly engaged and shouldn't require a strict IP warming schedule, a new domain still needs to establish its sending reputation to ensure these critical messages reach the inbox.

Key considerations

• Assess expected volume: Determine the projected daily and weekly sending volumes for your transactional emails. This will heavily influence the necessary domain warming strategy. High volume will require a more cautious approach.
• Consider domain age: Domains registered for less than three months are often viewed with more suspicion by ISPs.
• Leverage existing reputation: If you have an existing domain with a strong sending reputation, consider using a subdomain for your new transactional email program. This can leverage the parent domain's established trust and make domain warming significantly easier.
• Monitor deliverability: Closely monitor your sending reputation and inbox placement rates during the initial sending phase to identify and address any issues quickly. This includes checking for any domain-specific blocklistings. Understanding how domain and IP reputations interact is crucial.
• CRM provider support: Verify with your CRM or email service provider if their shared IP infrastructure can handle your forecasted transactional volumes without requiring a dedicated IP.

Key opinions

• Domain warming is essential: Marketers widely agree that even on shared IPs, a new domain needs warming. The general consensus is that any new sending configuration should be introduced gradually.
• High volume risks: Projected high volumes, even for transactional emails, are a significant red flag for new domains. A sudden influx of mail can cause delivery issues, including emails going to the spam folder.
• Transactional email considerations: While transactional emails are triggered and have high engagement, they still contribute to domain reputation. Therefore, an introductory period is advisable to prevent filtering by major consumer mailboxes. Twilio's guide highlights that low volume senders can use shared IPs and skip traditional warm-up, but a new domain changes this.
• Subdomain benefits: If an organization has an existing, well-reputed domain, using a subdomain for new transactional sends can significantly improve deliverability chances compared to a completely new top-level domain.

Key considerations

• Client constraints: Marketers often face limitations due to prior planning or system integrations, making it challenging to implement ideal warming strategies, such as using existing subdomains.
• Subscriber source: The source of new subscribers (e.g., website forms, social media sign-ups) can influence engagement and thus domain reputation. Organic, engaged sign-ups are always preferred for any new email program.
• CRM provider capabilities: It's crucial to confirm if the CRM or ESP can actually handle high projected volumes on a shared IP, or if they will push for dedicated IP addresses due to volume.
• Managing initial volume: Even with transactional emails, which are real-time, strategies for gradually increasing volume or prioritizing critical sends might be necessary for warming a new domain.

Key opinions

• Shared IPs are not warmable: Experts confirm that you cannot warm a shared IP address, as this is already handled by the service provider who maintains its reputation.
• New configuration needs warming: Any new email sending setup, particularly a new domain, should be warmed up. The aggression of the warming plan depends on the specific changes being introduced.
• Start slow and ramp up: Even for transactional mail, it's crucial to start with low volumes and gradually increase sending. Volume, cadence, and existing domain history are determining factors.
• Domain age matters for bulk sends: It is generally not advisable to send bulk messages from a domain registered for less than three months due to how ISPs view new domains with little history.
• High volume on new domains is risky: Sending high volumes, even tens of thousands, from a brand new domain is considered too much and can lead to immediate deliverability problems.
• Subdomains are beneficial: Leveraging a subdomain of an existing, well-established domain can significantly improve the chances of good inbox placement for new sending initiatives. This strategy is part of best practices for IP warming.

Key considerations

• Real-time mail flow: Transactional emails are typically real-time, making it difficult to throttle or manage their volume for warming purposes. This requires careful upfront planning.
• CRM provider's capacity: Always verify with your CRM or ESP if their shared IP setup is truly equipped to handle the forecasted high volumes on a new domain. Many may require a dedicated IP for such scale, impacting your deliverability strategy.
• No simple answers: Managing high volume growth with new configurations is complex and highly dependent on unique organizational factors, requiring tailored strategies rather than one-size-fits-all rules.
• Passive warming consideration: For lower volumes, a new domain might be able to warm passively through the organic growth of its subscriber base, assuming consistent positive engagement.

Key findings

• Shared IPs are pre-warmed: Documentation often states that shared IPs have already gone through a warm-up process and are continuously kept warm by the ESP, making IP warming unnecessary for senders using them.
• Domain warming is separate: Even when using a warmed shared IP, a new domain will need its own warm-up period to build reputation, as domain reputation is distinct from IP reputation.
• Volume sensitivity: Documentation implies that low-volume senders on shared IPs may skip warm-up, but for new domains, even transactional emails might require a gradual increase in volume to avoid deliverability issues.
• Establishing trust: The core purpose of warming is to gradually establish trust with mailbox providers, and this applies to the new domain's sending patterns.

Key considerations

• Guidance for new platforms: Guides from providers like Amazon SES emphasize the importance of warming best practices for both IPs and domains during migration.
• Dedicated IP recommendation: While shared IPs are pre-warmed, documentation often recommends dedicated IPs for high-volume senders or those who need more control over their sending reputation.
• Transactional email schedules: Some documentation suggests that transactional emails may not need a strict warming schedule since they are triggered. However, this primarily refers to IP warming, not domain warming.
• Impact of domain change: If you are changing your domain name, even if the IP address remains the same (or is a shared, warmed IP), expect that domain warm-up will be necessary. This is crucial for understanding your email domain reputation.