Double opt-in is a marketing practice that consists of asking a prospect’s consent, generally through electronic agreement by ticking a box, then confirming this consent by sending a confirmation email. The address becomes double opt-in when the recipient has clicked on the link in the confirmation email. This allows the address to the validated and to check that the person who provided it is the rightful owner. This double verification also confirms that the prospect truly wants to receive the newsletter or subscribe.
It is therefore recommended to use the double opt-in as it significantly reduces:
- the number of emails without a real impact (and thus the bandwidth consumed) - the load on the SMTP server when sending emails - the load on the server when handling unsubscriptions

Most object languages suggest standard getters and setters that the developer does not need to write.
Overloading them can increase the run and compilation time for these methods, which are generally better optimized by the language than the developer.
Consequently, use the standard getters and setters whenever possible, and implement methods that suit the purpose. This method has the added benefit of making maintenance easier for other developers, who will be more used to the behavior of standard getters/setters than those specifically implemented for the project.