When adding an RSS feed, the provided XML file is checked for validity (XML headers), but it's downloaded and parsed regardless of its size and content. This can lead to service unavailability and the cause is quite hard to discover since a very usual and tiny request can be used to trigger excessive system usage. Therefore, introduced a configurable limit defaulting to 4MB. RSS feeds larger than that limit will not be added and directly rejected.

# Defines the maximum feed size for an RSS feed in bytes
# Defaults to 4MB
com.openexchange.messaging.rss.feed.size=4194304