cmb wrote:So we might consider to apply the ToASCII conversion to the IDN before sending the mail.
This seems to be not as easy as expected. PHP offers the helpful function idn_to_ascii() only since PHP 5.3. This function is available as part of the intl and the idn packages too, but I'm in doubt, if these extensions are widely available. I found a class that can do the conversion in both ways, but it's 95 k uncompressed and works only with PHP 5.
As I'm not sure, if we need to implement the conversion, it's probably best to postpone the decision if and how we do it to XH 1.6.