MSN Hotmail now offers an optional supplementary storage space of 8 MB, for a total allowed mailbox size of 10MB increasing the overall storage to five times what you have today. Here's what 10MB of storage space in your Hotmail e-mail account can do for you: store more photos and attachments, keep the important e-mail messages you don't want to delete, send larger attachments...up to 1.5MB per message. All of this for only $12.95 a year.