In addition to the data protection rules that apply in the marketing context, marketers who rely on electronic methods of communication (such as email) must also comply with ePrivacy rules. The application of these rules mean that you need to obtain consent (and cannot rely on legitimate interests) in connection with email marketing. The GDPR’s standard of consent must be adhered to, because you’re dealing with personal data (i.e., consent must be specific, informed, unambiguous – pre-checked boxes or implied consent may not be enough). Additionally, recipients must always be provided with mechanism to opt-out.
For further details please see here.
Note that you may still rely on legitimate interests to conduct non-electronic marketing activities, such as via postal mail.
If you can answer yes to each of the questions above, you can send an email marketing communication to your desired recipient.
You may also be able to send the communication without positive /opt-in consent where the recipient of the email is a current customer and the content of the email relates to goods or services they have previously purchased from you (this is known as the 'soft opt-in'). In such case, you must still provide your privacy notice to the recipient and you must provide the recipient with an opt-out mechanism (usually both contained in prominent links at the bottom of marketing emails).