1. The Role of ISPs in Email Deliverability
The ISP (Internet Service Provider) is the person who controls the emails that reach the recipient’s mailbox. In Email Deliverability, the ISP is not the usual Internet provider, but rather email service providers such as Gmail, Hotmail, AOL, Yahoo Mail and the email systems of organizations.
Each ISP has its own evaluation criteria to decide whether an email is acceptable or not. They use different filters and anti-spam algorithms. Some ISPs publish their rules online.
The email sender’s job is to build credibility with the ISP. Without the trust of the ISP, the email marketing campaign will not reach the recipient, no matter how good the content.
2. Email Marketing Blacklists
Blacklists are databases of spam domains and IP addresses, maintained by specialized organizations such as Spamhaus, Spamcop or URIBL. ISPs use this data to classify spam emails.
Anti-spam service providers such as Google, McAfee and SpamAssassin have their own filters. Although ISPs do not disclose which blacklisting service they use, email senders can check and contact major organizations if they are blacklisted to request removal.
3. Spam Traps and How to Avoid Them
A spam trap is an email address that ISPs use to catch email marketers who are not following the rules.
There are two types:
- Recycled traps: Old abandoned email addresses that ISPs reuse to track email sending behavior.
- Pristine traps: Fake addresses placed on websites to detect illegal email harvesting.
To avoid spam traps:
- Don’t buy/rent suspicious email lists
- Don’t scrape websites for email addresses
- Check the source of your list carefully
- Develop a good email signup process
- Clean your list regularly
ISPs use spam traps to check if you are behaving like a spammer. Following the golden rule is the best way to stay out of trouble.
4. ISPs and the Three Factors That Evaluate Email
ISPs use spam filters to determine whether an email lands in the inbox. They focus on three main factors:
- Sender reputation
- Infrastructure
- Engagement
For effective email marketing, you need to build a strategy that optimizes all three of these factors. Doing this well will help you outperform your competitors in reaching your recipients.