IP Address
An IP address is a numeric label that identifies a device on a network. In email, the sending IP carries a reputation with mailbox providers.
An IP (Internet Protocol) address is a numerical label assigned to each device on a network. It identifies the device and gives other systems a way to reach it, which is how email and web traffic are routed.
Sending IPs and email
For email, the address that matters is the sending IP: the one receiving mail servers see your messages arrive from. Mailbox providers keep a history for each sending IP, and the reputation attached to that history influences whether mail from it is accepted. That is why a new or changed IP is warmed by ramping volume gradually rather than sending to a full list on day one.
On a shared pool, the reputation is shared with every other customer sending from those IPs. A dedicated IP belongs to one sender, so its reputation reflects only that sender’s mail, which also means low or irregular volume gives providers little history to judge it by.
Common mistakes
Switching IPs or sending platforms and then sending at full volume immediately. Moving to a dedicated IP to escape a shared pool’s problems without fixing the list or content that caused them. Blaming the IP when the domain is what appears on a blocklist.