I am using direct conversation with Port 25 to send bulk email.
However, some mail servers refuse unencoded umlauts in the header values and I can´t seem to figure out how to properly encode them.
All I could find was hints to the php mail function or some mailing libraries.
ContentType: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
I have tried
quoted_printable_encode
throws 'illegal character' Noticesutf8_encode
has no effect at alliconv_mime_encode($key, $val, ['scheme'=>'Q','input-charset'=>'ISO-8859-1']
leads to something like '=?UTF-8?Q?Dr=C3=BCnnen=20' in the Sender header, while subject and content are okay (at the problematic provider); but Thunderbird for my other account shows "�" in both list and detail view now. (the list view was okay without encoding)max(array_keys(count_chars($val, 1)))>126 && $val = "=?ISO-8859-1?q?". quoted_printable_encode($val);
-> shows as is at both recipients$val = '=?UTF-8?B?'.base64_encode($val).'?=';
almost does the trick; mails are accepted, unfortunately; Umlauts are still displayed as �
may add further examples during my tryouts. Any hints are very welcome.