Unable to send email

[sqdge]

Since I upgraded to the Stable release I have been unable to send emails. Looking in the error log it says:

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PHP Fatal error: Call to undefined function rcmail_deliver_message() in /home/*user*/public_html/mail/program/steps/mail/sendmail.inc on line 320
Line 320 is:

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$sent = rcmail_deliver_message($MAIL_MIME, $from, $mailto);
I'm sure that my SMTP settings are alright - any other ideas?