Full name suddenly taken as an address???

[Stephane Bortzmeyer]

Since a recent upgrade of PHP, IMP suddenly behaves strangely when the
user has a "Full name" configured (otherwise, everything is fine).

Mails are sent with the full name as the From: address. For instance,
in my case, people see my messages as:

From: Stephane@netaktiv.com, Bortzmeyer@netaktiv.com

Misc. information:

Horde : 1.2.6
IMP : 2.2.6
PHP : 4.0.100

(all of them regular and official Debian packages)

$default->custom_from_hook          = false;

The From of the mail envelope seems unaffected.