Is there an option to unsubscribe from receiving emails?

Yes. Prospects can opt out in a few ways:

• By replying. As soon as a prospect replies, Qualifier stops their sequence and they won't be contacted again by any campaign in your company. A line like "If this isn't relevant, just reply and let me know" is enough.
• With an opt-out link. Add the [opt-out-url] variable to your sequence or signature, for example <a href="[opt-out-url]">click here to opt out</a> in an HTML signature. Qualifier replaces it with a personal opt-out link. You can also use your own company's opt-out page if you have one.

If someone asks you directly to be removed from all future emails, they have that right under the GDPR. Add their address under Excluded email addresses (Settings, Company tab, Exclusions) to make sure they're never contacted again. See Exclude companies and contacts from your campaigns.