Subject of UTF-8 e-mails and avoiding spam filters

[vineld]

When sending UTF-8 e-mails using mail() I have previously used this for the subject in order to make it UTF-8 encoded:

 

$subject = "=?UTF-8?Q?".$subject."?=";

 

This worked fine for the lower case versions of the non-English letters of the Swedish alphabet although the upper case versions screwed it, displaying the full string above as the e-mail subject. I then tried this:

 

$subject = "=?UTF-8?B?".base64_encode($subject)."?=";

 

which seems to work just fine so far. Why is this? Will this work for all languages?

 

I am also looking for the best way to avoid being caught in spam filters since these are automatic e-mails sent by various membership systems. Which headers should I use? Currently I am using these:

 

From

Reply-To

MIME-Version: 1.0

Content-type: text/plain; charset=UTF-8

 

Unfortunately the system e-mails often end up in spam folders which is not that good. Any help or guidance would be highly appreciated.