[noprocrasted]

Lookup what's the email host of the destination address. Get a local account on it. If the provider supports scheduled sending, use that, otherwise use Telnet or automate the HTTP request to the webmail.

Being on the same provider will remove a lot of the variable delays in internet delivery. Scheduled send could also mean your email actually arrives in the destination inbox ahead of time but is just hidden until the required time (as it may all be one database under the hood).

If you can get 2 accounts on said provider, you can also test various strategies against your own accounts.

[9dev]

My reconnaissance has shown the server is in fact a self-hosted ESMTPD on a static IP address owned by Vodafone, but using a script to submit directly is a good idea!

[lucasluitjes]

If you want to beat other romantically inclined geeks running scripts, you could make sure your script is running somewhere with low latency to that static IP. Use traceroute, looking glass, tools to ping from multiple regions to find the perfect place to run your script.

A VPS in the same region with good peering would be a start. Could see what else is running on IP addresses in the same range, maybe find someone who runs infra on a nearby IP who is willing to run your script.