You can get an Estonian phone number through Twilio, MessageBird, Skype, or Travelsim (who offer Estonian SIM cards at a reasonable price).
You can purchase .ee domain(s) through Zone.
All physical mail you receive will be digitized and forwarded to you via email.
All business-related communication costs are considered business expenses and can be covered using your company's money.
How can I get an Estonian phone number or domain?