554 bosimpinc04 is on the Abusix Policy BlacklistWhat does 554 bosimpinc on the Abusix Policy Blacklist mean?
bosimpinc is the hostname prefix for Comcast’s Boston inbound mail proxy (Boston Inbound Mail Proxy, Inbound Connection). Numbered variants like bosimpinc01 through bosimpinc14 represent individual mail server instances in Comcast’s Boston ingress cluster. When Comcast returns this 554, your sending IP is listed on the Abusix Policy zone (one of the sub-lists of combined.mail.abusix.zone), and Comcast is rejecting based on that match. The fix is to delist at Abusix first, then if rejection persists, contact Comcast postmaster.
Is this a soft or hard bounce?
Comcast handles a large share of US consumer mail. A bosimpinc block affects comcast.net, xfinity.com, and related recipients routed through Boston ingress. Fixing the Abusix listing usually resolves the Comcast rejection within 24 to 48 hours.
Common causes
Most bosimpinc Policy listings affect IPs Abusix has marked as not authorized for direct mail. Switch to an authenticated relay.
Comcast aggressively checks SPF, DKIM, DMARC, and HELO matching PTR. Misconfiguration leads to policy listing.
Comcast feedback loop signals flow into the Abusix sensor network. High complaint rates cause listing.
How to fix it
Go to lookup.abusix.com and verify which Abusix zone lists your IP. The Policy zone is the most common for bosimpinc rejections.
If dynamic IP: switch to a relay. If misconfiguration: fix PTR, HELO, SPF, DKIM, DMARC. See 554 5.7.1 Abusix for full diagnostics.
Contact Abusix support through their portal with evidence of remediation. Policy zone removals are typically faster than Exploits or Blacklist sub-zones.
Submit a request at postmaster.comcast.net. Comcast usually defers to the upstream blocklist but can override in specific cases.
Provider-specific notes
| Recipient context | Notes |
|---|---|
| comcast.net consumer mail | Standard residential Comcast email accounts. Affected by all bosimpinc rejections. |
| xfinity.com, xfinitymobile.com | Same Comcast infrastructure. Same removal path. |
| Comcast Business Cable Email | Business accounts may route through different cluster (bizsmtp instead of impin). See walimpinc14 bizsmtp. |
Related error codes
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About the Author
Alaa · LinkedIn
Email infrastructure specialist with 8+ years of hands-on experience in SMTP, deliverability, and email verification. I’ve configured and troubleshot mail systems across Postfix, Exchange, and cloud relays, managed IP reputation and warmup campaigns, and built verification pipelines processing millions of addresses. My work spans DNS authentication (SPF, DKIM, DMARC, BIMI), bounce handling, blocklist monitoring, and compliance frameworks including CAN-SPAM and GDPR. I write every article on SMTPedia to give email professionals, developers, and marketers the accurate, RFC-grounded reference they need.
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