The API call https://accountname.sf-api.eu/sf/v3/Users(id)/ResendWelcome to re-send the welcome mail is a POST call. It has an id param (in the url) and a customMessage param. However, when trying to send this customMessage as a post variable (either www-encoded or json), it does not work. It only works when adding it with a ?customMessage=xyz to the URL. So it's a POST call but without any contents. Would it be possible to add the processing of the customMessage when sent in the POST data as well? Otherwise there is no reason for this api call to be of POST type. I hope that some day any api url could be used as POST, to work around the uri length limit.