How Does Email Marketing helps b2b businesses?

1. Collect e-mail addresses you're legally entitled to send mail to (different rules in different countries).
2. Prepare for receiving and processing bounces and opt-outs (especially if offering an opt-out is a legal requirement in your country).
3. Compose the mail.
4. Send it to your set of addresses.

That's all.

It is depend upon your business also, what kind of business you are dealing in?

Please make a good reporting format for representing your business, use professional language and provide your complete business address in the signature .

You can send to all the users using paid and free softwares to send large no. of clients. You can make contact with your customers through social media channels also.

Don't forget to collect relevant businesses in your database that are really interested in the offered product/solution. Having a targeted database is one of the most important things in making a successful email marketing campaign.