Email Glossary

IP Reputation

IP reputation is a score that ISPs and email providers assign to IP addresses based on their email sending history. IPs with good reputation deliver to inbox; those with poor reputation get blocked or sent to spam.

Shared vs Dedicated IPs

Shared IPs Multiple senders share the same IP address. Reputation is pooled, one bad sender can hurt everyone. Cost-effective but less control. Good providers carefully manage their shared pools.

Dedicated IPs You're the only sender on this IP. Full control over reputation. Requires warmup and consistent volume (50K+ monthly) to maintain. More expensive but isolated.

Multi-Tenant Reputation Isolation (Transmit approach) Per-customer reputation isolation without dedicated IP complexity. You get the benefits of isolation without managing IPs yourself.

Factors Affecting IP Reputation

Positive signals

  • ●Consistent sending volume
  • ●Low bounce rates
  • ●Low spam complaints
  • ●High engagement rates
  • ●Proper authentication

Negative signals

  • ●Spam trap hits
  • ●High complaint rates
  • ●Blacklist appearances
  • ●Erratic sending patterns
  • ●Authentication failures
  • ●Sending to old/invalid addresses

Checking IP Reputation

MXToolbox Check blacklist status across multiple blocklists.

Sender Score Provides a score from 0-100 for any IP.

Google Postmaster Tools Shows your IP reputation specifically for Gmail.

Talos Intelligence Cisco's tool for checking IP and domain reputation.

Check these periodically, especially before and after large campaigns.

Recovering IP Reputation

If your IP is damaged:

  • ●Identify the cause - Check logs for what triggered the issue
  • ●Request delisting - Apply to remove from blacklists
  • ●Reduce volume - Send only to most engaged users
  • ●Monitor metrics - Watch bounce and complaint rates
  • ●Gradually rebuild - Slowly increase volume like a warmup
  • ●Consider new IP - Severe damage may warrant starting fresh

For shared IPs, work with your provider. For dedicated IPs, you have direct control but also full responsibility.

Related Terms

Sender Reputation

A score ISPs assign to your sending IP and domain based on email behavior.

Email Warmup

Gradually increasing email volume to build sender reputation with ISPs.

Email Deliverability

The ability of your emails to reach recipients' inboxes instead of spam.

Email Blacklist

A database of IPs or domains identified as spam sources that ISPs use to block email.

Frequently Asked Questions

How do I know if my IP is the problem?
Check blacklist databases, review Google Postmaster Tools, and compare delivery rates to Gmail vs other providers. If you're on a shared IP, ask your provider about the pool's health.
Should I get a dedicated IP?
Only if you send over 50K emails monthly consistently. Below that, dedicated IPs can actually hurt, low volume makes ISPs suspicious. Quality shared pools or isolated sending solutions are better for moderate volumes.
How long does IP warmup take?
A new dedicated IP needs 4-8 weeks of gradual volume increase. Start with 50-100 emails/day and double weekly while monitoring metrics. Rushing warmup damages reputation faster than it builds it.
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Need help with email deliverability?

Transmit handles authentication, warmup, and reputation isolation automatically.