ok cool, you will find that in touch is dumping all of the messages into the Db now, it used to store them on the Capita servers but no longer because of data protection, there is a simple size on disk script you can run to determine how much it is taking up, and there is also a patch which will delete all messages older than a year old, (patch 22749) from capita, but after running the patch you need to shrink the database manually to claw back the size on disk
probably best to speak to capita also
Size on disk SQL script, run via SQL management studio and execute against the sims DB
SELECT
t.NAME AS TableName,
i.name as indexName,
sum(p.rows) as RowCounts,
sum(a.total_pages) as TotalPages,
sum(a.used_pages) as UsedPages,
sum(a.data_pages) as DataPages,
(sum(a.total_pages) * 8) / 1024 as TotalSpaceMB,
(sum(a.used_pages) * 8) / 1024 as UsedSpaceMB,
(sum(a.data_pages) * 8) / 1024 as DataSpaceMB
FROM
sys.tables t
INNER JOIN
sys.indexes i ON t.OBJECT_ID = i.object_id
INNER JOIN
sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id
INNER JOIN
sys.allocation_units a ON p.partition_id = a.container_id
WHERE
t.NAME NOT LIKE 'dt%' AND
i.OBJECT_ID > 255 AND
i.index_id <= 1
GROUP BY
t.NAME, i.object_id, i.index_id, i.name
ORDER BY
TotalspaceMB desc