Summary
Shifting email volume between IPs significantly impacts deliverability and IP reputation across different mailbox providers. While mailbox providers might not directly share data, the use of shared spam filters and blocklists can indirectly influence reputation. Abrupt volume shifts without proper IP warming are viewed as suspicious activity and can trigger spam filters. IP warming is essential to gradually build trust and establish a positive sender reputation. New IPs start with no reputation, emphasizing the need for a careful and gradual warming process. Consistent sending patterns are crucial to avoid being flagged as spam. Splitting volume across multiple IPs without a clear strategy can dilute reputation. Recent delivery changes to Outlook highlight that mailbox provider-specific updates can also impact deliverability, independently of IP-related actions.
Key findings
- IP Warming is Critical: A gradual and well-managed IP warming process is essential when shifting email volume to new IPs.
- Abrupt Shifts Harm Deliverability: Abruptly shifting email volume without warming can negatively impact deliverability and sender reputation.
- Indirect Reputation Influence: While mailbox providers may not directly share data, shared spam filters can indirectly influence reputation.
- Volume Changes Trigger Filters: Significant changes in sending volume from an IP can trigger spam filters at major mailbox providers.
- Reputation is Key: IP reputation is a key factor in determining inbox placement.
- New IPs Lack Reputation: New IPs start with no reputation and require careful management to build a positive one.
- Outlook Changes Impact Delivery: Mailbox provider specific changes, like those recently observed with Outlook, can impact delivery regardless of sender actions.
Key considerations
- Implement a Warming Strategy: Develop and implement a detailed IP warming strategy before shifting significant email volume.
- Monitor Reputation Metrics: Continuously monitor sender and IP reputation metrics to ensure deliverability is maintained.
- Maintain Consistent Sending: Maintain consistent sending patterns and adhere to established SMTP standards.
- Avoid Diluting Reputation: Avoid splitting email volume across too many IPs without a clear and well-defined strategy to prevent diluting reputation.
- Stay Updated on Provider Policies: Stay informed about the deliverability and spam filtering policies of major mailbox providers, as they can change and impact delivery.
- Start with low volume: Start warming with low volume and slowly increase it over time.
What email marketers say
11 marketer opinions
Shifting email volume between IPs can significantly impact deliverability and IP reputation across different mailbox providers. While mailbox providers don't directly share data, indirect influences through shared spam filters or blocklists are possible. Abrupt shifts without proper warming can trigger spam filters as mailbox providers view the activity as suspicious. Warming is essential to establish a positive sender reputation gradually. Splitting volume across multiple IPs without a strategy may dilute reputation. Consistent and gradual warming processes are crucial for new IPs to avoid deliverability issues.
Key opinions
- IP Warming Crucial: Proper IP warming is essential when shifting email volume to a new IP.
- Sudden Shifts Harmful: Abruptly shifting email volume without warming can negatively impact deliverability and reputation.
- Indirect Data Sharing: While providers don't directly share data, shared spam filters can indirectly influence reputation.
- Volume Changes Trigger Filters: Changes in sending volume can trigger spam filters at major mailbox providers.
- New IP Reputation: New IPs start with no reputation, making warming critical.
Key considerations
- Warming Strategy: Develop a gradual IP warming strategy before shifting significant email volume.
- Reputation Monitoring: Monitor sender reputation metrics to ensure deliverability is maintained.
- Consistent Sending: Maintain consistent sending patterns to avoid triggering spam filters.
- Traffic Quality: Ensure traffic sent from any IP address is high quality to avoid negative impacts.
- Diluted Reputation: Avoid splitting volume across too many IPs without a clear strategy to prevent diluting reputation.
Marketer view
Email marketer from StackExchange shares that splitting email volume across multiple IPs without a proper strategy can dilute your reputation and make it harder to achieve good inbox placement.
1 Aug 2022 - StackExchange
Marketer view
Email marketer from Mailjet shares that a sudden increase in email volume from a new IP can trigger spam filters at mailbox providers like Gmail, Yahoo, and Outlook, and suggests gradually increasing volume over time.
12 Jan 2025 - Mailjet
What the experts say
4 expert opinions
Shifting email volume to new IPs requires careful management, including a structured warm-up process to build a positive sending reputation with ISPs. IP reputation is a key factor in filtering decisions. Recent delivery changes to Outlook suggest that mailbox provider updates can impact deliverability, regardless of IP shifts. Warming practices need to be carefully managed, starting with low volume and gradual increases.
Key opinions
- Outlook Changes: Recent changes in Outlook delivery indicate that mailbox provider updates can impact deliverability.
- IP Reputation Crucial: IP reputation is a vital factor in filtering decisions made by mailbox providers.
- New IPs Require Warm-up: New IP addresses need a structured warm-up process to establish a positive sending reputation.
- Warming Balance: Warming practices require a delicate balance, starting with low volume and gradual increases.
Key considerations
- Manage New IPs: Carefully manage new IPs with structured warm-up processes.
- Monitor Reputation: Continuously monitor IP reputation as a key indicator of deliverability.
- Adapt to Changes: Be prepared to adapt to changes in mailbox provider filtering policies.
- Gradual Warming: Warm up IPs gradually, starting with low volume and slowly increasing it over time.
Expert view
Expert from Email Geeks shares that several people have noted a change in delivery to Outlook over the last couple weeks, suggesting changes on Microsoft's end and coincidental timing.
15 Oct 2023 - Email Geeks
Expert view
Expert from Word to the Wise explains that IP reputation is important because many, many filters use IP address to make filtering decisions. It’s just one tool, but it’s a commonly used one.
30 Jun 2021 - Word to the Wise
What the documentation says
4 technical articles
Sending email from a new IP address can impact deliverability, highlighting the importance of following IP warming best practices to establish a positive sender reputation with Gmail. Microsoft also emphasizes that IP reputation is a key factor in determining whether email is delivered to the inbox or spam folder, and a sudden change in sending patterns can harm reputation. SMTP standards stress consistent sending patterns to avoid being flagged as spam. Monitoring sender reputation metrics and gradually increasing email volume when shifting between IPs is suggested to maintain deliverability.
Key findings
- IP Reputation Matters: IP reputation is a key determinant of inbox placement.
- New IPs Impact Deliverability: Sending from new IPs can negatively impact deliverability.
- Consistent Patterns: Consistent sending patterns are crucial for avoiding spam filters.
- Warming is Essential: IP warming best practices are necessary to establish a positive sender reputation.
Key considerations
- Monitor Metrics: Monitor sender reputation metrics regularly.
- Gradual Increase: Increase email volume gradually when shifting IPs.
- Follow Best Practices: Adhere to IP warming best practices.
- Maintain Consistency: Maintain consistent sending patterns.
Technical article
Documentation from SparkPost suggests monitoring sender reputation metrics and gradually increasing email volume when shifting between IPs to maintain deliverability and avoid triggering spam filters.
15 Mar 2022 - SparkPost
Technical article
Documentation from RFC Editor outlines SMTP standards and best practices for email sending, highlighting the importance of consistent sending patterns to avoid being flagged as spam.
15 Jan 2023 - RFC Editor
Are IP warming services effective for improving email deliverability?
Do ESPs charge for dedicated IPs and how much do dedicated IPs cost?
Do I need an IP warm-up when moving to a new ESP with shared IPs?
How do email volume and volume fluctuations affect deliverability and sender reputation?
How do ESPs manage IP pools and how does it affect deliverability?
How do I warm up a new IP address for transactional emails?
How do I warm up new IP addresses for email sending?
What deliverability improvement can be expected from using dedicated vs shared IPs?
When should I use a shared IP address over a dedicated IP address for email sending?
