This seems to work OK:

[setantae@archaia setantae]$ cat barf
#!/usr/bin/perl -w
$normal = "text here";
$at = "setantae\@eidosnet.co.uk";
$caret = "something^with a caret in";
write STDOUT;
format STDOUT =
@<<<<<<<<<<<<<<<<<<<<<<<<<<<<< @<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< @<<<<<
+<<<
$at, $caret, $normal
.
[setantae@archaia setantae]$ ./barf
setantae@eidosnet.co.uk        something^with a caret in        text h
+ere
[download]

You need to escape the @ (which -w would have told you (yeah, yeah, no use strict;, but I'm trying to keep it short)).

setantae@eidosnet.co.uk|setantae|http://www.setantae.uklinux.net