I'm migrating a mailing service from a server to another. Before setting up new mailing list I wanted to process it through an email validtor I've setting up on the server.
I basically used this tool (Mass email validation) that works in 3 steps :
- syntaxic validation
- domain name validation (MX record)
HELOandRCPT TOcommansd (SMTP protocol) to simulate a mail-send to the address that grants the address in particular in reachable
After a couple of tests I realised that there was issues with this validtion method. I tried running the process twice on the same initial batch and the results were different.
I noticed that addresses with very common domain like gmail.com, hotmail.com would tend to fail at the third step, especially at the end of the batches.
It seems like those servers simply block my requests systematically after a certain amount of requests, like my server becomes blacklisted.
If I wait a few hours before starting a new batch, emails that have failed previously will be correctly validated, like there was a cap limitation to the number of requests in a given time period.
Is there some "official guideline" about email validation to avoid such problems ?
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