Summary
Achieving granular control over sending volume and speed per ISP is generally limited with major SaaS transactional SMTP providers like Mailgun, SendGrid, SparkPost, and Amazon SES. These providers offer tools for managing sending reputation and deliverability, indirectly influencing ISP-level delivery. Options for direct ISP-level throttling include running your own server using PowerMTA, Postfix, or Exim (requiring advanced technical skills and resources), leveraging GreenArrow, SocketLabs (enterprise tier) or considering smaller providers with caution. Building a custom solution provides the highest control but requires significant expertise. Careful evaluation of needs and technical capabilities is essential.
Key findings
- Limited Direct Control: Major SaaS ESPs generally do not offer direct ISP-level control over sending volume and speed.
- Indirect Control Options: Major ESPs provide tools for managing sending reputation and deliverability that indirectly influence ISP-level delivery.
- Self-Managed/Custom Solutions: Running your own server (PowerMTA, Postfix, Exim) or building a custom solution provides the highest degree of control, but demands significant expertise and resources.
- Smaller Providers: Smaller providers might offer more flexibility, but their reliability needs thorough evaluation.
- Alternative Providers: GreenArrow and SocketLabs offer configurations and rule engines that can potentially enable more granular control.
Key considerations
- Technical Expertise: Self-managed and custom solutions require substantial technical expertise in server administration, email protocols, and deliverability.
- Resource Allocation: Assess the resources (time, personnel, budget) needed for building, maintaining, and monitoring custom setups.
- Reputation Management: Maintaining a good sending reputation is critical regardless of the chosen approach.
- Needs Evaluation: Evaluate specific sending needs and technical capabilities before selecting an ESP or custom solution.
- Provider Reliability: Carefully assess the reliability and reputation of any smaller, less-known providers.
What email marketers say
13 marketer opinions
The ability to granularly control sending volume and speed per ISP is generally not a standard feature offered by major transactional SMTP providers like Mailgun, SendGrid, SparkPost, and Amazon SES. These providers offer tools for managing sending reputation and deliverability, such as IP pools, routing rules, dedicated IPs, and segmentation, which can indirectly influence ISP-level delivery. For direct ISP-level throttling, options include running your own server with software like PowerMTA, Postfix, or Exim (requiring significant technical expertise), or using smaller, lesser-known SMTP providers, although their reliability and reputation should be carefully evaluated. GreenArrow and SocketLabs are also mentioned as potentially offering more granular control.
Key opinions
- Limited Control with Major Providers: Major SaaS transactional SMTP providers typically do not offer direct ISP-level control over sending volume and speed.
- Indirect Control Methods: Providers offer tools like IP pools, routing rules, dedicated IPs, and segmentation to manage deliverability, indirectly influencing ISP-level delivery.
- Self-Managed Solutions: Running your own server with software like PowerMTA, Postfix, or Exim allows for the highest degree of control but requires significant technical expertise.
- Smaller Provider Option: Smaller, lesser-known SMTP providers might offer more flexibility but require careful evaluation of their reliability.
- Alternative Providers: GreenArrow and SocketLabs have features that potentially enable more granular control over sending configurations and routing rules
Key considerations
- Technical Expertise: Self-managed solutions require significant technical expertise in server administration, email protocols, and deliverability management.
- Reputation Management: Maintaining a good sending reputation is crucial for deliverability, regardless of the chosen provider or setup.
- Scalability: Consider the scalability of the chosen solution as email volume grows.
- Cost: Evaluate the total cost of ownership, including infrastructure, software, and personnel, for both SaaS and self-managed solutions.
- Provider Reliability: Thoroughly assess the reliability and reputation of any smaller or lesser-known SMTP provider.
Marketer view
Email marketer from Twilio SendGrid Help Center explains that SendGrid doesn't allow direct ISP-level throttling. However, features like IP management, dedicated IPs, and segmentation enable senders to optimize deliverability which could indirectly affect sending to specific ISPs.
20 Nov 2023 - Twilio SendGrid Help Center
Marketer view
Email marketer from SocketLabs explains that you can configure custom processing/routing rules using their Rule Engine (available on enterprise-tier service plans)
2 Aug 2023 - SocketLabs
What the experts say
2 expert opinions
Experts from Word to the Wise indicate that achieving granular control over sending volume and speed per ISP is challenging with most ESPs. Building a custom solution offers the most control but demands substantial technical expertise and resources. Therefore, evaluating specific needs and technical capabilities is crucial when selecting an ESP.
Key opinions
- Limited ESP Control: Direct control over sending volume and speed per ISP is generally limited with most ESPs.
- Custom Solution Advantage: Building a custom solution provides the highest degree of control.
- Resource Intensive: Custom solutions require significant technical expertise and resources.
Key considerations
- Technical Capabilities: Assess the technical capabilities needed for implementing and managing custom solutions.
- Resource Allocation: Evaluate the resources (time, personnel, budget) required for building and maintaining a custom solution.
- Needs Assessment: Carefully evaluate specific sending needs before choosing an ESP or custom solution.
Expert view
Expert from Word to the Wise explains that while some ESPs may offer certain levels of customization, direct control over sending volume and speed per ISP is generally limited. She recommends carefully evaluating the specific needs and technical capabilities before choosing an ESP.
25 May 2023 - Word to the Wise
Expert view
Expert from Word to the Wise suggests that building your own custom solution, possibly leveraging open-source MTAs or a hybrid approach, provides the highest degree of control over sending volume and speed per ISP but requires significant technical expertise and resources.
23 Sep 2021 - Word to the Wise
What the documentation says
3 technical articles
PowerMTA, Exim, and Postfix provide options for configuring delivery settings at the domain or IP level, enabling the implementation of ISP-specific throttling. Each offers flexible configuration for managing sending rates and concurrency, but this requires advanced knowledge and manual configuration.
Key findings
- ISP-Specific Throttling: PowerMTA, Exim, and Postfix support configuring delivery settings to implement ISP-specific throttling.
- Flexible Configuration: Each platform offers flexible configuration options for managing sending rates and concurrency.
- Manual Configuration: Implementing ISP-specific throttling requires manual configuration in all three platforms.
Key considerations
- Advanced Knowledge: Configuring these platforms effectively requires advanced knowledge of email systems.
- Manual Effort: Setting up ISP-specific throttling involves significant manual effort.
- Maintenance: Ongoing maintenance and monitoring are necessary to ensure optimal performance and deliverability.
Technical article
Documentation from PowerMTA explains that PowerMTA allows configuring delivery settings at the domain or IP level, which can be used to implement ISP-specific throttling. It supports flexible configuration for managing sending rates and concurrency based on various parameters.
21 Jun 2024 - PowerMTA
Technical article
Documentation from Exim details how to configure rate limiting and concurrency settings. Exim's flexible configuration enables defining different sending rates per domain or IP, allowing for ISP-specific settings, though this requires manual configuration.
2 Jul 2021 - Exim
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