I would like to extract, the next 140 characters (excluding whitespace and newlines) after a keyword eg. "START".

my ($foo) = $mailbox =~ /START((?:\s*\S){140})/;
[download]

This matches START followed by 140 non-whitespace characters, each of which can have any amount of whitespace in front of it.

- Yes, I reinvent wheels.
- Spam: Visit eurotraQ.