Definition
ISP relationship management refers to the deliberate effort of building and maintaining a positive sender reputation with individual internet service providers and mailbox providers. While much of deliverability is automated by reputation algorithms, having established channels for communication with provider postmaster teams can be the difference between resolving a delivery issue in hours versus weeks.
Large-volume senders often maintain direct contacts at major providers through postmaster programmes. Smaller senders benefit from following each provider's published sender guidelines, monitoring feedback loops and responding rapidly to any deliverability warnings.
Key ISP Relationship Channels
- Google Postmaster Tools for Gmail deliverability data and reputation monitoring
- Microsoft SNDS for Outlook and Hotmail reputation data
- Yahoo Complaint Feedback Loop for spam complaint monitoring
- Individual provider sender guidelines and best-practices documentation
Best Practices
- Register for every provider's postmaster tools and review data weekly — not just when a problem is suspected
- Follow each provider's published sender requirements to the letter; major providers increasingly require specific authentication configurations
- If a deliverability issue requires contacting a provider, present structured data including authentication records, complaint rates and engagement metrics
- Treat ISP relationships as an ongoing maintenance activity, not an emergency-only channel
Related Glossary Terms
Bounce Classification
Bounce classification uses SMTP codes (550, 551, 552, 553, 554, 450, 451, 452) and enhanced status codes to categorise permanent and transient delivery failures.
DMARC Alignment
DMARC identifier alignment determines whether the domain in the From header matches the domains used in SPF and DKIM authentication. Strict or relaxed.
Acceptance Rate
Acceptance rate is the percentage of emails submitted for delivery that are accepted by the recipient's mail server, representing the first deliverability checkpoint before inbox placement is determined.
Email Acceptance Rate
Email acceptance rate measures the percentage of emails accepted by recipient mail servers versus total sent. It is a core deliverability metric that reveals whether your sending infrastructure is trusted by receiving servers.
Email Account Health Score
A composite metric that evaluates the overall health of an email sending programme based on deliverability, engagement, list quality, and compliance factors.
Email Active Subscriber
An active email subscriber has opened or clicked an email within a defined recency period, typically 30-90 days by industry. Active subscriber rate of 40-60% is typical for healthy email lists.