Sending card numbers by email is a very bad idea!
Agree could be if not sure who / how it might be used and you have unencrypted mail client/service.
I use
Proton mail which is encrypted, and its via our family owned server.
I first via phone verified the source of the service. Made initial membership via phone providing banking details to enroll. Follow up renewals i've done via email providing bank details. No issues.
I initially struggled to get membership but found online this person whom I later thanked for source of information.
" Hi Dave
Thank you for your email so pleased you are sorted with your membership of ADAC.. The other lady is Amanda Moser-Wickles and she is the Office Manager sometimes she has to make visits to other Offices etc., and is away for a few days. which means Ann-Katrin is in the Office Full time. Ann-Katrin is a very efficient lady I met her when visiting the Office in April this year. I have known Amanda getting on for 10 years now and visiting the Office when on our annual trip to Germany each year..
The sad thing is it is difficult to get through to the Regensburg Office due to they only have one telephone line and sometimes there is an answerphone on but sometimes you are put through to other offices. Most other Offices do not have the capabilities of taking cards due to the Germans are not allowed to pay that way. Due to me complaining some 8/9 years ago finding it difficult to renew our Membership Munich Head Office set Regensburg up as the office to deal with British Membership and the capability of taking Debit/Credit Cards.
Kind Regards
Dianne
www.joysofeuropeancaravanning.co.uk"
Persons could follow this advice for their renewals if they do not have secure e-mail services :
https://www.joysofeuropeancaravanning.co.uk/adacbreakdownservice.htm
Note also on this link information confirming that new memberships were unobtainable for other than persons living in Germany from 1st Out 2017.