Activesync qustion

I just signed up for Zoho mail and have configured activesync on my iPhone (iPhone5, iOS 8.3). It appears to sync but will only sync back about 6 months. I have confirmed that the emails are there for that time period and the contacts are syncing. I have also confirmed that imap syncs the entire mailbox. I administer Exchange where I work and we only sync back one month so I have not tested this anywhere else. Is this normal behavior?