Hi james-devs, I just created this issue: https://issues.apache.org/jira/browse/MIME4J-253 I also have problems where some email-clients send headers like this: To: =?iso-8859-1?Q?_f...@gmail.com=2c_f...@hotmail.co.uk=2C?= =?iso-8859-1?Q?_kr...@gmail.com=2c_l...@domain.com?= Which should decode to (and tested with http://dogmamix.com/MimeHeadersDecoder/ although not an authoritative validator): To: f...@gmail.com, f...@hotmail.co.uk, kr...@gmail.com, l...@domain.com I don't really know whether it's valid to have the address-list-separator (comma) as part of the encoded value but most email-clients parse this successfully and so should Mime4J, don't you think? Appreciate any views/comments on this, thanks. -- Andreas Joseph Krogh CTO / Partner - Visena AS Mobile: +47 909 56 963 andr...@visena.com <mailto:andr...@visena.com> www.visena.com <https://www.visena.com> <https://www.visena.com>