email security

I have transitioned to an icloud email address on my iMac and iPhone and rarely send or receive emails at my old comcast.net account.  It’s important to me to keep this old email account separate from the new icloud account for security reasons – too many years of suspicious activity, phishing scams and general spam.

Because of this I went into my Mail app on my iMac and unclicked ‘Enable this account’ under account preferences.  I also see my account listed as inactive on the preferences window as well.

I was hoping to be able to log in to my Xfinity email account on the internet and still be able to see the occasional legitimate emails I might get on the old comcast.net account, but when I log in over the past week or so, all folders are simply noted as empty.

Is this account now dead?  Is there a way I can still log in to see activity on this old account without having to make the account active again on the Mail app? 

I see an option called Auto Forward but I would rather not activate that feature because, as mentioned above,  I would like to keep the comcast.net account totally separate from the icloud account for security reasons.  I’m not certain if I were to activate Auto Forward, that I would be 100% certain that anybody emailing the old comcast.net account would not be able to simply see the new icloud address and thereby gain access to all my addresses, contacts and activities going forward?