Even if you’re sending as few as 25 e-mails from Microsoft Outlook or your e-mail client, as “news” or a “newsletter” e-mail, you could easily get your IP address blocked, preventing future e-mails from getting delivered to your customers – even if you’re just sending a single e-mail. First, let’s understand three important definitions –
IP Address: An IP address is a series of numbers assigned to a device connected to the internet to obtain host/network identification and location. ISPs will use your IP address to determine where your e-mails are coming from. Here’s how to find your IP address.
ISP: An Internet Service Provider (ISP) is the company that provides your connectivity to the internet. Each ISP can, and usually does, have their own spam filtering systems. See a list of the top ISPs in the US.
Whitelisting: Each ISP’s spam filtering system works in part by asking those who send bulk e-mails (which can be as little as 25 e-mails sent in a short burst of time) to apply for approval to send such mass e-mails in a process known as “whitelisting”.