I had an email in my inbox today from Shutterfly with a subject in Base-64 encoding. Only, the subject was so long in Base-64 that it didn’t all fit on a single line in the email headers. Which means my base-64 subject decoder needs to be a little more robust.
The raw-header looks like this:
Subject: =?UTF-8?B?WW91ciBUaGFuayBZb3UgZ2lmdCBlbmRzIFdlZC4gfCBFbmpveSA=?=
=?UTF-8?B?JDIwIGp1c3QgZm9yIHlvdcKg?=
Notice anything odd about the format of this header? Each line has it’s own encoding tags, instead of one encoding tag spanning both lines, so it’s a little different than what I’ve seen on long subjects encoded with quoted-printable. Converted from Base 64 to English, the subject should parse into:
Your Thank You gift ends Wed. | Enjoy
$20 just for you
No weird special characters or anything that really necessitates base-64, but none the less to be a robust email parser, this kind of case should probably be handled.
In Delphi, I get a single string with the entire header except the word “Subject: “, but including the line break returned from Indy. This means I can’t just say from after the B? to the very end minus two characters, I need to actually tokenize the ending question-marks and/or whitespace, and encoding begin strings, perhaps in a loop, so I can pull out just the base 64 encoded part:
WW91ciBUaGFuayBZb3UgZ2lmdCBlbmRzIFdlZC4gfCBFbmpveSA=
JDIwIGp1c3QgZm9yIHlvdcKg
And then pass that lovely string into the base64 decoder. And then instead of a subject of
=?UTF-8?B?WW91ciBUaGFuayBZb3UgZ2lmdCBlbmRzIFdlZC4gfCBFbmpveSA=?= =?UTF-8?B?JDIwIGp1c3QgZm9yIHlvdcKg?=
you could have a subject of
Your Thank You gift ends Wed. | Enjoy $20 just for you