Does SecureMyEmail encryption make my email GDPR compliant?

Yes! Encryption is a key suggested method within the GDPR. Specifically, it says one should take “appropriate measures” to keep personal data secure and to perform the required ‘pseudonymization’ of stored data,:

SecureMyEmail surpasses these requirements and provides end-to-end encryption that fully protects your email, and all attachments, whether they are in transit or archived on your (or your provider’s) servers.