Rails 2.3.2 <=> 2.3.4 SMTP: Recipient cannot contain spaces

Did something change within the mailing support in Rails between
versions 2.3.2 and 2.3.4?

I have an app running Rails 2.3.2 with the following string as 'sender'
for every email I sent out (new user created, forgotton password, that
kind of thing)
MAIL_FROM = "MyAwesomeWebsite.com <automailer@myawesomewebsite.com>"

This works fine and in all mail programs I have used it displays the
'pretty' MyAwesomeWebsite.com as the sender, with the automailer@... as
the address.

Now that I have upgrades to 2.3.4 (or 2.3.5 for that matter) I always
get the error:
(Net::SMTPSyntaxError) "501 syntax: Recipient cannot contain a space
(<\"MyAwesomeWebsite.com\" <automailer@myawesomewebsite.com>)\n"

Anyone got an idea what is causing this? The error talks about
recipient, and not sender. Have some order of parameters been swapped
sneakily inbetween these 2 rails versions?