Marketing globally requires an understanding of what you are allowed to send and with what provisions. Your marketing technology should help track individuals that have Opted In to your solicitation but it is up to the marketer to decide who receives the solicitations based on the location of the subject.
United States: The United States is governed by the CAN-SPAM Act and is occasionally referred to as the "You-Can-Spam" Act because it allows marketers to send solicitations until the recipient “Opts Out.” In particular, it does not require marketers to obtain permission before they send marketing messages. It also pre-empts individual states like California from requiring an Opt-In.
California created the (CCPA) to give consumers more control over the personal information that businesses collect about them. In particular, the CCPA guarantees the consumer’s right to know about the personal information a business collects about them, the right to delete personal information collected, and the right to opt-out of the sale of their personal information. It does not however, require a business to collect an Opt-In before solicitation.
Canada: Canada is governed by CASL or the Canadian Ant-Spam Legislation passed in 2014. In short, the legislation requires a business to have consent from the recipient before sending a solicitation. It is important to note the law protects Canadians, but can impact businesses outside of Canada.
Europe: The GDPR or General Data Protection Regulation is a European Union law designed to protect European citizens. The GDPR is a much more comprehensive law that distinguishes between data controllers and data processors with responsibilities for both. Data Controllers (direct marketers) usually work under legitimate business interest to process personal data and ask for their permission for solicitation. Data Processors must allow for a consumers right to be forgotten or understand how their data is processed.
In the larger spectrum, think of the US as the least stringent and the emailers responsibility is to observe Opt Outs. The most stringent is Canada - where marketers must first obtain consent to send an email. The middle ground is Europe. The GDPR allows for marketers to ask for consent to receive solicitation, provided there is a legitimate business interest.