Great class which works really well, this has saved me a load of time.
I integrated this class into a local application a couple of years ago with great success, however there does seem to be an odd bug.
If an email (usually spam) has been sent to dozens of email addresses, with each appearing in the To field, an error is caused which actually crashes Apache. Every time our email receiver runs (which happens every ten minutes) the same happens, causing quite a lot of grief. I've only ever encountered this 3 times, and the number of emails received per day runs into several hundred.
For clarity, I am not extracting this element of the header or processing it, I believe it stems from here $head=$obj->getHeaders($t);