Check your sending IP is not on any email blacklists

15 min Impact: medium Effort: low ✓ Manual completion

Your sending IP reputation is tracked separately from your domain reputation, and a blacklisted sending IP causes real deliverability problems, legitimate email landing in spam or being rejected outright, regardless of how well your domain-level authentication is configured.

Shared hosting or shared email sending infrastructure means your IP reputation can be affected by other users on the same infrastructure, worth checking directly rather than assuming it is fine.

The full picture

IP-based email blacklists represent a distinct, additional dimension of email deliverability risk beyond domain-based blacklisting discussed elsewhere — your sending IP address, whether dedicated or shared with other senders depending on your email infrastructure, can independently end up on blacklists that affect your email deliverability regardless of your domain's own reputation status.

This distinction matters particularly for shared sending infrastructure, where your deliverability can potentially be affected by other senders' behavior on the same shared IP address — a genuinely well-managed sending domain can still experience deliverability issues if the shared IP infrastructure it uses has accumulated reputation problems from other senders' activity.

Regular verification of your specific sending IP against major blacklist services provides genuine, direct visibility into this risk dimension — this check complements rather than duplicates domain blacklist verification, since IP and domain reputation, while related, represent genuinely distinct evaluation criteria different mail systems may weight differently.

Where a genuine listing is identified, remediation depends significantly on whether you control dedicated sending infrastructure or use shared infrastructure through a third-party email service — dedicated infrastructure requires your own direct remediation and delisting request, while shared infrastructure issues may require working with your email service provider, who has their own genuine interest in maintaining their shared infrastructure's overall reputation.

How to do it

1

Identify your actual sending IP

Check your email service provider settings, or the headers of a test email you send to yourself.
2

Check it against major IP blacklists

A dedicated blacklist checking tool covers dozens of lists at once.
3

If listed, investigate the real cause

Could be your own sending practices, or on shared infrastructure, another user entirely.
4

Request delisting once the cause is resolved

Each blacklist has its own removal request process.

Common mistakes

On shared hosting or shared email infrastructure, your sending IP reputation can be damaged by someone else's bad behavior entirely outside your control, worth confirming with your provider if this happens repeatedly.