If one is simply looking to ping (i.e. perform an SMTP check) on email addresses, which is what the companies listed above all do, then you’re not going to be solving your deliverability problems.
Deliverability issues are the result of five main factors in the following order of priority:
- The existence of spamtraps and/or honeypots
- Excessive spam complaints – .3% (i.e. 300 complaints out of 100,000 sends) is the typical threshold used by ISPs.
- Exceed this threshold and a dynamic block will be put up, preventing the delivery of any future emails for 24-48 hours.
- Exceed this multiple times and you’ll find yourself blocked and/or blacklisted for good.
- Exceeding bounce rate thresholds – 10% is the typical threshold used by ISPs but this can vary significantly across ISPs, some of which are also factoring engagement metrics into this calculation and their determination of whether or not you’re a worthy sender.
Pinging is discouraged by many ISPs, which will shut down attempts over a certain number or provide back inaccurate information so any service that simply performs pinging only might result in more issues than you first started with as you will end up throwing out good addresses with the bad. Furthermore, pinging an email address, even if this could be 100% accurate, will not flag spamtraps, honeypots, heavy spam complainers, “role” accounts that go to multiple accounts, and other malicious addresses that can destroy one’s email program.
Accordingly, marketers need to employ a service that blocks deliverable but toxic addresses, corrects hygiene errors, and validates all email addresses that survive the first two screens. Doing this properly requires expertise, experience, technology, and a knowledgebase built over years of reviewing billions of email addresses.