If used appropriately, Smart Email Verifier, will not put you in any spam list. I'll try to explain, how we are avoiding spam list.
First, we provide the HELO string. This provides the correct IP and e-mail, improving better lookup and accuracy.
By default, Smart Email Verifier does a syntax and domain level verification. If you use the default, this will never generate any kind of black listing.
If you change the default to do SMTP verification then Smart Email Verifier uses the VRFY (verify) SMTP command to lookup the mailbox. This command is the legal way of checking if a mailbox exists or not. Many SMTP servers, who do not want you to respond to a VRFY command, will simply state that the command is not implemented.
In this case, you can choose to use Smart Email Verifier's "Forced SMTP Verification" option. This type of forced verification option, which is used by other e-mail verifiers as the default, may be thought of as spam by some SMTP servers. Smart Email Verifier gives you more options and lets you decide your own level of e-mail verification.