So, We have patch for review which works towards allowing the current STMP/ESTMP server implementation to be sublcassed in order to implement ESMTP extensions. Here is the ticket https://twistedmatrix.com/trac/ticket/8128 If you care about SMTP/ESMTP please send your feedback, here or on the ticket. I am not an SMTP/ESMTP expert and I need help in reviewing this ticket. ------- My main questions regarding ESTMP extensions are : 1. Do we really want to implement them using sublcassing or using composition/interfaces/components ... or something else? ------ 2. From https://en.wikipedia.org/wiki/Extended_SMTP#Extensions Each service extension is defined in an approved format in subsequent RFCs and registered with the IANA. Are there ESTMP servers in the wild which provide extensions which are not defined by RFCs? Do we want to encourage multiple implementation for the same extensions or encourage people to collaborate toward a single implementation which is hosted by Twisted? -------- Thanks! -- Adi Roiban