If this is the same mail provider listed in your profile (ends with ".ca"):
To my knowledge, they use POP3, a mail technology from 1996.
POP3 only provides access to the Inbox, and only the Inbox.
No Sent / Deleted, or additional incoming folders.
No sync of read/unread message states.
Feel free to contact them and ask about IMAP (a more modern way to access mail, which Aqua supports).