A customer configured big enough outgoing and/or incoming message size limits for their Hosted Exchange mailbox, like on the screenshot below:
However, customer cannot send/receive messages whose size is well within configured limits, e.g. 10 MB message cannot be delivered while a customer configured 100 MB limits on incoming/outgoing messages.
An attempt to deliver message to customer's mailbox results in the error message:
#550 5.2.3 RESOLVER.RST.RecipSizeLimit; message too large for this recipient ##