Only list collection when sending out access notification

When you share a collection with other people and they are notified about it, they receive a notification listing every single page within that collection (see example below). It would be better if the notification only included the collection title and not the page titles.

Listing page titles may be OK for a collection containing just 2-3 pages, but not for one that contains 10 or more.

Current notification:

You have been sent a notification from Mahara. Message follows:
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Subject: New access to pages "HCI experiment 1", "HCI experiment 2", "HCI
experiment 3"

You have been added to the access list for the pages "HCI experiment 1", "HCI
experiment 2", "HCI experiment 3" in collection "HCI experiments" by Paula Paulsen

See [URL]

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Better:

You have been sent a notification from Mahara. Message follows:
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Subject: New access to a portfolio

You have been added to the access list for the collection "HCI experiments" by Paula Paulsen

See [URL]