Closing my Gmail account

I want to get rid of my 15 year old Gmail account and only use my personal mail address on my private domain,, but it's been especially hard to transfer all my contacts and all services over. Can't just cut the cord... and delete the Google account alltogether, right?

Using the "vacation" mode of Gmail to inform people in my contacts list of my intentions, yet still I get many emails addressed to Keeping track of contact details is hard for everyone.