To avoid your emails being treated as spam, does it help to attach a vcf file?

Sorry but no, adding a VCF with your contact information doesn't help your emails to go through spamfilters (i.e. be classified as 'ham').

I think you should split the question into two parts, there is the "content" side, i.e. how to lay out the message content so that it looks legit, and there is the "server config" site, i.e. how your servers should be set up.

I actually only know about the latter part, the server configs. And I don't feel it appropriate to discuss it here, it's IMHO off topic. (And if you search around on Serverfault.com & Stackoverflow.com and you will see it very well described there.)

While I don't want to discuss the technical aspects of server configuration here, it may be useful for others if I write up a short list of what needs to be done. Here it is, make sure that:

• You're sending emails from a server with a permanent, public IP address.
• The server has reverse DNS properly set up.
• The server isn't blacklisted for present or past violations of the Internet standards.
• You have set up SPF records for your domain, to 'whitelist' the servers that are allowed to send emails for you.

The simplest and fastest way to handle the above is to use 1-2 good hosted mail service providers. Don't set up mail servers yourself, it's too much work and the spammer / antispam battle rules are constantly changing. A good common config for many new startups is:

• Google Apps for Domains as your main email provider, for 1-on-1 business email. If you have a webapp that needs to send emails (like account confirmation emails), then send these via Google Apps via their APIs.
• A newsletter service provider like fx MailChimp for newsletters etc.
• A SPF record for your domain, which links Google Apps' SPF records into your own.