Peter as I understand the GDPR it is based on this:
https://en.wikipedia.org/wiki/General_Data_Protection_Regulation
Please note: The regulation was adopted on 27 April 2016. It becomes enforceable from 25 May 2018 after a two-year transition period and, unlike a directive, it does not require national governments to pass any enabling legislation, and is thus directly binding and applicable.[3]
The proposed new EU data protection regime extends the scope of the EU data protection law to all foreign companies processing data of EU residents. (my note here... you can sometimes but not always tell from an email address if the person is from a country in Europe. So this is where the email issue gets thorny)
and this is the stated scope:
The regulation applies if the data controller (an organization that collects data from EU residents) or processor (an organization that processes data on behalf of data controller e.g. cloud service providers) or the data subject (person) is based in the EU. Furthermore the regulation also applies to organizations based outside the European Union if they collect or process personal data of EU residents. According to the European Commission "personal data is any information relating to an individual, whether it relates to his or her private, professional or public life. It can be anything from a name, a home address, a photo, an email address, bank details, posts on social networking websites, medical information, or a computer’s IP address."[6]
Consent[edit]
Where consent is used as the lawful basis for processing, consent must be explicit for data collected and the purposes data is used for (Article 7; defined in Article 4). Consent for children[15] must be given by the child’s parent or custodian, and verifiable (Article 8). Data controllers must be able to prove "consent" (opt-in) and consent may be withdrawn.[16]
(my note: I think the question here is if the consent currently being given has information that is specific enough for the GDPR to consider it an informed consent)
Pseudonymisation[edit]
The GDPR refers to pseudonymisation as a process that transforms personal data in such a way that the resulting data cannot be attributed to a specific data subject without the use of additional information. An example of pseudonymisation is encryption, which renders the original data unintelligible and the process cannot be reversed without access to the correct decryption key. The GDPR requires that this additional information (such as the decryption key) be kept separately from the pseudonymised data. Pseudonymisation is recommended to reduce the risks to the concerned data subjects and also help controllers and processors to meet their data-protection obligations (Recital 28).
Although the GDPR encourages the use of pseudonymisation to "reduce risks to the data subjects," (Recital 28) pseudonymised data is still considered personal data (Recital 26) and therefore remains covered by the GDPR.
The sanctions can be quite heavy. so the question is, how much do we want to gamble on WikiTree and my response is that is not up to us it is up to Chris.
Right to erasure[edit]
A right to be forgotten was replaced by a more limited right to erasure in the version of the GDPR adopted by the European Parliament in March 2014.[20][21] Article 17 provides that the data subject has the right to request erasure of personal data related to them on any one of a number of grounds including non-compliance with article 6.1 (lawfulness) that includes a case (f) where the legitimate interests of the controller is overridden by the interests or fundamental rights and freedoms of the data subject which require protection of personal data (see also Google Spain SL, Google Inc. v Agencia Española de Protección de Datos, Mario Costeja González).
Data protection by Design and by Default[edit]
Data protection by Design and by Default (Article 25) requires that data protection is designed into the development of business processes for products and services. This requires that privacy settings must be set at a high level by default and that technical and procedural measures should be taken care by the controller in order to make sure that the processing, throughout the whole processing lifecycle, complies with the regulation. Controllers should also implement mechanisms to ensure that personal data is only processed when necessary for each specific purpose.
over 80 percent of those surveyed expect GDPR-related spending to be at least $100,000.[30] These concerns were echoed in a report commissioned by the law firm Baker & McKenzie that found that "around 70 percent of respondents believe that organizations will need to invest additional budget/effort to comply with the consent, data mapping and cross-border data transfer requirements under the GDPR."[
I say again, if it was my money I would consult an international rights and permissions attorney with background in digital security and privacy issues.