In NeetoCRM, you have lead/deal/contact-specific emails present by default. You don't need to connect any of your email accounts for this.
For example, if you have not synced any of your accounts, go to any Lead show page -> Mails -> Send email here you'll see a lead specific email in from option something like [email protected].
Any emails sent or forwarded to this email address will be associated with the lead and can be seen on the lead's mails tab and also on the lead/deal specific mails list. Go to Mails -> Lead/Deal specific emails to see the mail list for leads and deals.
For contacts, you have a separate tab i.e. Contact specific emails .
On the right-bottom page of the particular lead/deal/contact page, you can see the email widget which shows the specific email address. There is an option to regenerate this specific email address as well.
You can disable this lead/deal-specific email feature ie by going to Admin panel -> Configure -> Lead/Deal specific emails.