If a tool shows one of your sending IPs on a blacklist, it's almost always a non-issue:
We use dynamic IP rotation — IPs change throughout the day — so a tool may be flagging a previously-used IP while your current sending IP is different and unaffected. Your actual sender IP lives in other DNS records, not the A record many tools check.
Rotation is reputation-driven: we track the reputation and blacklisting status of every IP in the pool and rotate IPs out whenever needed, so a listed or poor-reputation IP doesn't stay in your sending path. You don't need to monitor or manage sending IPs yourself — we handle that entirely on our side. Because the pool is shared and centrally managed, we can't move an individual account to a different pool or assign a dedicated IP — see Can I get a dedicated sending IP for my mailboxes?
Some of our IPs will always be listed somewhere. We send 80M+ emails a day for cold outreach, and that footprint means a share of the pool is on one list or another at any given time — Spamhaus CSS, SBL or XBL, Barracuda, and similar. That's the nature of the business, and the system is designed around it: listed IPs are rotated out automatically and don't affect what you send. A routine blacklist check that finds 10–20% of our IPs listed is normal and not something to react to.
UCEPROTECT (e.g. UCEPROTECTL3) flags entire hosting networks, not individual senders — even clean senders and Google's own IPs appear there. It broadly flags 50–60% of the internet, including platforms like Netflix, and mailbox providers ignore it. It has no real impact on cold email deliverability.
"Listed IPs are in your SPF record"
If you audit the SPF record on your domain, you'll find it authorizes a large range of IPs, and some of those will show as blacklisted. That's expected: the SPF record lists every IP that may send for the domain, not the ones currently in use. Once an IP gets listed we stop routing mail through it, but it can stay in the SPF record — pruning SPF on every rotation isn't practical at our volume and isn't necessary, because an IP that isn't sending can't affect your placement. A Spamhaus listing that stays active for weeks on an IP in your SPF simply means that IP has been out of rotation for weeks.
"PTR / reverse DNS is missing"
Audit tools regularly flag our sending IPs for missing or invalid PTR (reverse DNS), or for a bare IP in HELO. That's by design, not a misconfiguration: PTR records only exist for fixed IPs, and we rotate, so they'll always look missing on our pool. Gmail, Outlook and Yahoo evaluate DKIM, DMARC and SPF — all of which are set up correctly on your domains — not rDNS. Some sender guidelines list rDNS as a requirement; in practice it doesn't change placement from our infrastructure, which has run this way since day one. Our DKIM and DMARC records are also custom-built for our own SMTP servers, so some tools call them "generic" or "non-standard" — you can verify them yourself at mxtoolbox.com or easydmarc.com. AI-based audit tools in particular are trained on older, single-server setups and tend to flag a high-volume rotating pool as "wrong" when it isn't.
What's actually worth checking
The reliable way to check your own standing is to look up your domain (not an individual IP) against a blocklist — a point-in-time IP snapshot mostly tells you about an address that may already be out of your sending path. And even then, the domain lists people worry about most — SURBL and Spamhaus DBL — no longer affect inbox placement at Google or Microsoft either; see SURBL Listings and Deliverability Impact. If you want one honest measure: run an inbox placement test from the mailbox itself. That tells you where your mail actually lands, which is the only thing a blacklist flag is a (weak) proxy for.
If you're still concerned, contact support and we can share your current rotated sending IP — see also Can you give me the IP addresses of your sending servers? for why we don't publish a static list.
Seeing real placement problems, not just a flag? If your emails are actually landing in spam or being rejected, send us your account email, the affected domains or mailboxes, what flagged them (a screenshot helps), one full message header or your latest placement-test result, and your current warmup settings — we'll look at the actual cause rather than the flag. You can also book a Deliverability Audit with one of our specialists: log in, click the Deliverability Audit button in the top-right of your dashboard, and pick a time.
For the bigger picture on "burned" labels and blacklist flags, and how to tell a false alarm from a real problem, see My mailboxes show as "burned", "blacklisted", or low reputation — what it means.