An Internet Service Provider or ‘ISP’ is the term email markers use to describe an email provider. This term was coined in the early part of the development of email as Internet Service Providers were hosting these systems. As the email environment has grown, this once accurate description no longer best describes this space. Below is a quick breakdown of the various types of systems today and some of the unique rules that apply:
Internet Service Providers:
- Example: Comcast, Cox, Charter
- Description: These providers are today’s truest description of an ISP. With an internet subscription, a customer will receive an account for personal use. This account is dependent on having an active subscription. Once the user leaves the service, the ISP has the right to disable the user access.
- Unique Detail: ISPs, due to their size and system, offer email as an afterthought. These ISPs, because of resources, will often use third-party vendors to bridge the gap between their system and the Global Mailbox Providers today. As a result, when seeing deliverability issues, a customer can expect to see a performance issue at all other regional ISPs. That is because these providers will leverage the same firewall or reputation network to address spam (Example: Barracuda, Cloudmark).
Mailbox Providers - Global:
- Example: Gmail, Yahoo, Microsoft
- Description: Mailbox provider is a free service that allows anyone to sign up and create an account. These accounts often times come with promotional ads and other various restrictions.
- Unique Detail: Global Providers, due to the type of service, will disable an account after a period of inactivity. This ranges on the system, but the rule of thumb is one year of inactivity and the mailbox will move to a disabled state (550s).
Email Clients (Vanity Mail):
- Example: Office Outlook, Mobil Devices
- Description: With the introduction of IMAP (Internet Message Access Protocol), customers have even more freedom in how and where they see their emails. This works by moving mail from the receiving system (ISP) to an outside web client.
- Unique Detail: This can add a layer of complexity when it comes to reputation filtering and rules. This is because the primary mailbox provider AND the Email Client can both apply reputation based rules to a received message.
Premium Service Providers:
- Example: Google Apps, Office365
- Description: These accounts are traditionally B2B (@yourdomain.com). They tend to leverage both the in-house and external firewalls to troubleshoot and resolve spam and malicious messages. Firewalls are systems, which sit in front of a receiving mail server, to filter and scan for possible malware and malicious messages.
- Unique Details: Premium Service providers are very sensitive to authentication and content when applying filtering rules. They, also, leverage third-party services to help bridge the gap when identifying and stopping spam from getting delivered.