If you try to post on the FieldTrip email discussion list and get the following error:
You are not allowed to post to this mailing list, and your message has been automatically rejected. If you think that your messages are being rejected in error, contact the mailing list owner at fieldtrip-owner AT donders.ru.nl.
This is most likely due to having sent the email from another email address than the one with you used when registering. The email list server cares about the details of the address, so firstname.lastname@example.org is considered to be a different person than email@example.com. A similar change in email addresses is firstname.lastname@example.org, which changed into email@example.com.
Please check very carefully on which email address you are receiving the postings from the fieldtrip list, and what you have configured as the “from” address in your email client. If that does not resolve it, please contact the list owner.