Summary
When sending a remarkably large email deployment, such as 6 million messages, on shared IP addresses, the need to send in batches largely depends on the specific practices of your Email Service Provider (ESP) and the established warm-up of their shared IP pools. Unlike dedicated IPs which often require a methodical IP warming process from scratch, shared IPs are typically already warmed by the collective sending of many users. However, sudden, unusually large spikes in volume, even on shared infrastructure, can sometimes trigger monitoring systems or throttling, so it is prudent to understand your ESP's capabilities. The primary concern shifts from IP reputation to the recipient's website infrastructure if the email campaign drives significant traffic.
Key findings
- ESP consultation: The definitive answer on whether to batch a large send on shared IPs almost always comes from your ESP. They manage the shared IP warm-up and overall reputation, understanding the capacity of their infrastructure. They can advise on how to manage sending volume for larger email campaigns without issues.
- Shared IP warm-up: Shared IP addresses do not typically require the same individual warm-up process as dedicated IPs because they are continuously used and maintained by the ESP across many senders. This means they are often already warmed up for consistent volume.
- Transactional vs. marketing: The type of email (transactional or promotional) can influence how an ESP handles volume, though for large reputable ESPs, this distinction might be less critical for overall IP health than the sending patterns.
- Website traffic consideration: A key factor, especially for deployments of millions of emails, is the potential impact on your website or server infrastructure due to simultaneous clicks and traffic spikes. This often becomes a more immediate concern than email deliverability on well-managed shared IPs. For more information on this, see how to manage large email sending volume spikes.
Key considerations
- ESP capacity: Rely on your ESP's guidance, as large providers like Mailchimp are typically equipped to handle massive volumes on their shared IP infrastructure without requiring special batching from the sender's end, provided the list quality is good.
- Load balancing: Discuss load balancing with your ESP. They can often distribute the load across multiple shared IPs or send at a rate that aligns with their system and receiving mailbox provider capabilities, effectively batching it on their side.
- Unusual volume: If this volume is highly unusual for your sending patterns, communicate this to your ESP. While they might handle the volume, being transparent can help them prepare or offer specific advice.
- Impact on sender reputation: Even on shared IPs, poor list quality (high bounces, spam complaints, spam traps) from a large send can negatively affect the overall reputation of that shared pool, impacting all senders. This is why batching email sends can sometimes improve deliverability indirectly by allowing early detection of invalid addresses.
What email marketers say
Email marketers often discuss the delicate balance between sending speed and deliverability, especially when dealing with large lists on shared infrastructure. While the general consensus leans towards trusting your ESP to manage shared IP performance, concerns about volume spikes and their impact on sender reputation frequently arise.
Key opinions
- Trust your ESP: Many marketers believe that established ESPs, particularly large ones, have sophisticated systems to handle substantial email volumes on shared IPs without requiring individual senders to manually batch, suggesting that 6 million emails should be fine.
- ESP consultation is key: Despite general assurances, marketers consistently advise checking directly with your ESP for confirmation. This is crucial because a shared IP's capacity for handling large sends is heavily dependent on how extensively it has been warmed up and managed by the provider.
- Website load impact: A significant point raised is that the primary concern for very large email deployments might not be email deliverability itself, but rather the ability of your website to handle the sudden influx of traffic generated by the email campaign.
- Batching for deliverability: Some marketers suggest that sending in smaller batches can help ESPs detect invalid email addresses early in a campaign, preventing potential deliverability issues.
Key considerations
- Unusual volume: If a 6 million email deployment is an anomaly for your sending patterns, this fact should be communicated to your ESP. While they may have the capacity, understanding your typical volume helps them manage expectations.
- Load balancing responsibility: Marketers recognize that ESPs are responsible for load balancing on shared IPs. Direct communication allows the ESP to properly distribute the immense volume across their infrastructure, minimizing any negative impact.
- Shared IP selection: For small lists, a shared IP is generally the best option as it is typically already warmed up, reducing the risk associated with sending too many emails too quickly from a new IP.
- Email type: The nature of the emails (e.g., transactional versus promotional) can affect how they are handled, particularly if there are unsubscribe bypass considerations. This is more of an ESP policy concern than a direct deliverability one for the user.
Marketer from Email Geeks asks if batching is necessary for an unusually large 6-million email deployment on shared IPs and, if so, how many batches would be ideal.
Marketer from Email Geeks suggests that a 6-million email send on shared IPs should generally be acceptable, indicating that the ESP's infrastructure is likely robust enough.
What the experts say
Experts emphasize that while shared IPs are managed by the ESP, large or unusual sending patterns still warrant careful consideration. They highlight the importance of communication with the ESP and list quality, even when relying on shared infrastructure. The discussion often turns to the broader context of a sender's overall email program and how unusual volumes fit within it.
Key opinions
- ESP load balancing: Experts agree that communicating with your ESP is crucial so they can effectively load balance the large deployment across their shared IP infrastructure. This proactive step helps ensure smooth delivery.
- Shared IP capabilities: Experienced professionals often note that shared IPs, especially from major ESPs, are designed to handle significant volumes. The primary factor is the ESP's ability to warm and manage these IPs for collective use.
- Website robustness: A key point for very large sends is the necessity for your website or landing page infrastructure to be robust enough to withstand the expected surge in traffic. This can be a greater bottleneck than email delivery itself.
- Sender behavior: Even on shared IPs, consistent high engagement and low complaints are vital. Experts highlight that poor sending habits, even from a single sender in a shared pool, can negatively affect all users on that IP, potentially leading to IP blocklisting.
Key considerations
- Warm-up status: The existing warm-up status of the shared IPs is critical. Your ESP should confirm whether their shared pools are adequately warmed to handle a 6-million email deployment without issues. If your ESP's shared IPs are not consistently used for high volume, managing sending volume carefully is key.
- Email type and recipient behavior: While transactional emails might have different rules, a sudden large send, even of transactional nature, to a list that doesn't usually receive this volume requires consideration regarding recipient engagement and potential negative feedback.
- Spike volume management: Even on shared IPs, sending large volumes of emails all at once from a 'cold' IP (or one not accustomed to such a spike) can signal spam-like behavior to ISPs. Reputable ESPs proactively manage this to protect their shared pools.
- List hygiene: Maintaining a clean and engaged list is paramount for email deliverability, regardless of whether you're using a shared or dedicated IP. A high-volume send to a poorly maintained list can quickly lead to blocklists and reputation damage.
Expert from Email Geeks recommends directly consulting with your ESP for confirmation, as the necessity for batching heavily relies on how well the shared IPs have been warmed up to handle the proposed volume.
Expert from Email Geeks advises the sender to speak with their ESP to facilitate load balancing for the large deployment, reassuring them that the send will likely proceed without major issues.
What the documentation says
Official documentation and industry guides provide foundational knowledge on shared versus dedicated IPs, IP warming, and best practices for large email sends. They generally confirm that shared IPs are managed for collective reputation, but also highlight risks associated with sudden, large, or poorly managed sends, even within a shared environment. The core principle remains consistent: maintaining a positive sender reputation is paramount, regardless of IP type.
Key findings
- Shared IP basics: Documentation defines a shared IP address as being simultaneously used by multiple senders, with all data transmitted via the same server. This allows a large pool of senders to collectively contribute to the IP's reputation.
- IP warming differences: Shared IP addresses typically do not require the individual IP warming process that dedicated IPs do, as the ESP handles the collective warm-up and maintenance. However, this also means senders have less direct control over the IP's trustworthiness.
- Volume and reputation: Sending large volumes of emails all at once from a 'cold' IP or one not accustomed to such a spike can appear as spam-like behavior to Internet Service Providers (ISPs), regardless of IP type, and can quickly lead to blocklists or filtering.
- Dedicated IP for scale: For senders who routinely deliver more than 50,000 emails per month, documentation suggests a dedicated IP is generally necessary to establish and cultivate their own sending reputation. This is where the choice between dedicated IP vs. shared IP becomes more significant.
Key considerations
- Gradual volume increase: Even for large campaigns, the principle of starting slowly and progressively increasing mail volumes (known as IP warming) is a fundamental best practice to establish trust with ISPs, though on shared IPs this is managed by the ESP.
- Sender reputation management: The ISP's assessment of a sender's behavior, especially if engagement is low or spam complaints rise from a large send, can lead to suspicion of spam-like activity, regardless of whether a shared or dedicated IP is used.
- List quality impact: Poor list quality can severely impact deliverability. Sending to non-existent email addresses, particularly in large volumes, can result in high bounce rates and potentially land your IP (or the shared IP) on a blacklist or blocklist.
- Reliable ESPs: Using a robust Email Service Provider is crucial, as they manage the complexities of shared IP reputation, including warming and load balancing, to ensure optimal deliverability for their clients.
Documentation from IPXO states that shared IP addresses do not necessitate a warm-up procedure, but they inherently provide less direct control over the IP's overall trustworthiness compared to dedicated IP addresses.
Documentation from Webbula warns that excessively rapid email sending from a new IP address can lead Internet Service Providers to suspect spam-like activity, particularly when coupled with low engagement or increased spam complaints.
