What is this Perl string encoded in?

Question

I'm using use Mail::IMAPClient to retrieve mail headers from an imap server. It works great. But when the header contains any character other that [a-z|A-Z|0-9] I'm served with strings that look like this :

• Subject : Un message en =?UTF-8?B?ZnJhbsOnYWlzIMOgIGxhIGNvbg==?= (original string : "Un message en français à la con")

• Body : =C3=A9aeio=C3=B9=C3=A8=C3=A8 (original string : éaeioùèè)

  1. What is this strange format ? Is that the famous "perl string internal" format ?
  2. what is the safest way of handling human idioms coming from IMAP servers ?

Answer 1

The body encoding is Quoted-Printable; the header (subject) encoding is MIME "encoded-word" encoding ("B" type for base64). The best way to deal with both of them is to pass the email into a module that's capable of dealing with MIME, such as Email::MIME or the older and buggier MIME::Lite.

For example:

# $message was retrieved from IMAP
my $mime = Email::MIME->new($message);
my $subject = $mime->header('Subject'); # automatically decoded
my $body = $mime->body_str; # also automatically decoded

However if you need to deal with them outside of the context of an entire message, there are also modules like Encode::MIME::Header and MIME::QuotedPrint.