Basically there are no clear guidelines for this but several verdicts in the past have clarified that such consent cannot be valid indefinitely. Unfortunately past legislation has named periods between 4 weeks (fax) and 10 years – so there is no useful legally approved indication existing. Furthermore, several legal experts argue that, similar to a patient’s provision, a consent once given should be valid indefinitely.
To have a practical clue we recommend to rather remove unused addresses from your mailing list for good if they are older than 1 year, instead of suddenly submitting advertising emails to them. Since it can be assumed that the subscriber will not remember giving consent nor having any more interest in finally receiving the sender’s advertising emails, this will help in avoiding unnecessary complaints and spam classification.
Posted in: Legal issues