Update error when sending mail

Thanks for noting this. The problem is related to my use of an update immediately after the node with the mail is created. (I did this so that the email would include information on what roles it was sent to).

Perhaps the problem is caused by Postgresql locking the newly-created record?

To disable this update (and therefore end the error message), delete or comment out (put two forward-slashes in front of) the line:

        db_query('UPDATE {node} SET body = "<p>' . t('This email was sent to users with the following roles: ') . implode(', ', _mail_get_roles_names($node->roles)) . '</p>' . $node->body . '" WHERE nid = %d', $node->nid);

I've made the update database-specific (i.e., won't update if database type is pgsql). This should solve the error, though I don't have a pgsql installation to test on.