An IP address's neighbourhood
An IP address never stands alone. It belongs to an address block, the block belongs to an autonomous system (AS), and that AS has an operator with a history. For spam filters this membership is a concrete signal: new, unknown IPs are not judged in a vacuum but by the reputation of the network they came from.
That explains an effect many people trip over: a freshly leased, never-used IP address can deliver badly from day one — not because of anything it did, but because of the neighbourhood it sits in. Conversely an IP inside an established email service provider's address space starts with a substantial head start.
What AnalyzeMy.Email checks
- AS number for every IP, for IPv4 and IPv6 alike
- Operator name — the registered holder of the autonomous system
- Country and registry — RIPE, ARIN, APNIC, LACNIC or AFRINIC
- Allocation date of the block
Lookups run over Team Cymru's DNS service, so no HTTP call to a third-party web service is involved. It is not only the sending IP that is resolved but every address derived from the SPF record, and for ranges the block's network address. In the report every AS number is clickable and loads its details on demand.
What you can read from it
Does the operator match the sender? A message supposedly from a bank, sent from a budget hoster's address space, is a flag — not proof, but a data point alongside SPF and DKIM.
How many networks are in your SPF record? If the resolved IPs are spread across eight different AS, you are sending through eight infrastructures. Each of them can damage your reputation, and each is exposure should one of those services be compromised.
Shared or dedicated? A large provider AS usually means shared outbound IPs: your deliverability then depends on how every other customer behaves. Your own IP in your own block gives you full control — and full responsibility, because it has to be warmed up first.
Practical consequences
- Check before you move: anyone switching to a new sending IP should know whose network it sits in and how that network is regarded.
- Separate transactional from marketing mail — ideally across different networks, so a campaign cannot drag your password reset messages down with it.
- Factor it into warm-up: in a well-regarded network this goes faster. In an unknown block it takes more patience and smaller steps.
- On a listing, check whether the whole block is affected. Some lists carry entire ranges — a delisting request for a single address will not help then.