If an IP is found in the listed RBL, then the IP is considered blacklisted by MX Toolbox which is an external service that we monitor 24/7 for updates. If an IP we manage is blacklisted, we will work to remove the blacklist or change the mail delivery IP address.
If you are using a SOCKS proxy server to send mail, you need to check their IP addresses.
Remember - you need to check the sending IP and domain name.
What if the server isn't listed, but emails are bouncing anyway?
If an email is blocked due to the actions of the recipient's network, the recipient needs to contact their provider to resolve the issue. Email providers that block IP addresses and domains do so at their discretion and generally only take steps to unblock requests from their own customers, not requests from third parties. If this happens, it's best to contact the recipient by other means and send them a copy of the bounce message so they can forward it to their provider.
Some providers block entire IP ranges or even countries in an effort to reduce spam. Not only is this highly impractical, it's also ig database a very basic approach to solving the spam problem. There are many other best practice approaches to reducing spam that go beyond simply blocking IP addresses.
This protocol is important to marketers because it directly affects the emails you send and their deliverability.
If this all sounds a little daunting, don't worry - although SMTP is a highly technical subject, this guide will teach you what you need to know from a less technical perspective so that you can better understand how it affects your email marketing.
The Many Faces of SMTP
Although the acronym SMTP actually refers to the communications protocol that mail servers use to transmit electronic messages (that is, email) over the Internet, the term is also used interchangeably to mean the following:
SMTP (protocol)
SMTP Relay
SMTP Server
Read on to learn the differences between the three.
SMTP protocol
As we mentioned above, SMTP primarily refers to the set of rules that a mail server uses to transfer email messages from the sender's SMTP server over the Internet to the correct receiving SMTP server, where the recipient can access the message through their email inbox client.
More specifically, the protocol works like this:
Specify the sender and receiver of the message
Send a request to the sender and receiver to verify that they exist
Messages are sent from sender to recipient
The steps for transmitting a message over the Internet according to SMTP (for those who really want to know)
If you’re a marketer, you’re probably not interested in the details of how SMTP works in practice. But if you want to shine in your next meeting with your tech team, here’s a more detailed process.