Linode Ubuntu mail server idea

Im on a comcast account blocking port 25, i could redirect and forward everything home to another port and keep my mail at home.

would having the Linode only open to mail ports and have all other ports even ssh closed be a good idea?

i was thinking about setting up a (PF sense firewall) VPN and having the Linode connect on boot giving its self a IP next to all my other stuff thus if i need to ssh i could do so like anything else at home.

leaving it only open to receiving mail.

i do want to keep some kind of past 3 running days on the linode incase i need to reboot my home mail box?

any thoughts or sage advice?