An apparatus for inserting a document into an envelope. The apparatus includes a mechanism for holding an envelope at an insert station; pivotally mounted fingers for opening the envelope; and a platform for guiding the document over the fingers and into the envelope. The platform is pivoted at an upstream end and upwardly spring biased so that the platform is depressed against the spring bias, by an amount dependent on the weight of the insert document moving over, so that a light insert document follows a path which subtends a steeper angle to the horizontal compared to a heavy insert document.