Yes, there is a maximum 20MB message size. An incoming message over 20MB will be bounced and returned to the sender.
You will need to review your mailbox storage quota to ensure you have enough space to receive emails. You can check the mailbox storage you have used by logging into your mailbox and at the bottom of the screen you can see the percentage of storage space you have used. If your mailbox gets to 2GB then you will need to delete some of your emails to free up more storage space so that you can continue to receive emails.