Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
by agreeing to become a member you opt-in to receiving occasional special offer , marketing , survey and product based communication emails . 

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. OPTIONS: ["Contract by using", "Unilateral change", "Content removal", "Jurisdiction", "Unilateral termination", "Limitation of liability", "None", "Choice of law", "Arbitration"].