I agree with getting in touch, I just don't agree with spending your time each day doing it.
Occasionally, there is reason to do a little research into the customer's operations (e.g. visiting their website) from which I can add a personal twist.
If you do it that way, it's not a huge time suck.
Here's what wrecks the experience:
1) The email comes from info@example.com instead of your personal company email account.
2) The email does not contain your normal signature, complete with email and phone number.
3) The email contains too much custom info (nothing more than the customer's name). No real person would take the time to cut and paste a customer's custom URL, for example.
4) HTML emails, unless they are very plainly styled. It needs to look like a regular friendly email.
5) Any sort of marketing speak. Has to be in your actual voice, as if you were talking with a friend. It's not a sales pitch, but an opportunity to connect.
6) Getting the name wrong! Just because there is a name field doesn't mean your customers put their name in it. This is the main automation killer. Better to have no name at all than the wrong name or "Dear Admin User"
7) The email is too long or contains anything that a reasonable person would assume was cut and pasted in.
8) Not asking any questions - if you don't ask questions, you're less likely to get an answer.
I'm sure there is more, but this recipe works reasonably well for me.
When bootstrapping a startup that you want to be able to scale, automating everything that can be automated is very important.
I answer a lot of mail and I make sure that I always refer to something in the original email that is unique to the writer. That goes a long way to getting out of the 'form letter' rut and the response is much better than with emails that contain no 'personal note'.
In the early days of the internet, I may have fallen for something like that... only to realise my reply went to a ticket support system or a fake 'from' address. Nowadays, I'm cynical about welcome messages and just delete them.
Also you may see someone you know.