Sender Policy Framework

Can I run an SMTP server on my laptop?

If you run a personal domain, you can either not publish SPF records at all, or set up "v=spf1 ?all" for your domain, and you'll be able to send mail from your laptop no matter where you are. A better solution would be to set up your own smtp server that accepts mail from your laptop through POP-before-SMTP or SASL AUTH, so that you can still publish a more restrictive spf record.

If you are the customer of an ISP that publishes SPF records, your ISP should provide you with an SMTP server that you can authenticate to, using either POP-before-SMTP or SASL AUTH. Or you can ask them to exclude you from SPF using a user-specific "exists" mechanism.