B2B cold email: a practical guide and the legal side (2026)

What B2B cold email is

B2B cold email is a commercial email sent to a business or professional you have not been in contact with before. It is used to open a conversation: introduce a service, suggest a call or ask who the right person is.

First: the legal side

Rules on unsolicited commercial email vary by country, and they often apply to business recipients too. In Spain, for example, article 21 of the LSSI (Spanish e-commerce law) prohibits promotional emails that were not "previously requested or expressly authorised" by the recipient, and the law defines a recipient as a natural or legal person — so it covers companies, not just consumers. The main exception is an existing customer relationship involving similar products or services, with an easy, free way to opt out.

Public data is not, by itself, permission to contact someone commercially. If an address identifies a person (firstname.lastname@company.com), data protection law such as the GDPR also applies. This is not legal advice: check the rules of the country you are sending to before you run an email campaign.

Alternatives when you sell to local businesses

Because of those rules, many companies selling to local businesses in Spain use other first-contact channels and keep email for people who have shown interest:

• Phone. Many local businesses publish a phone number even when they have no useful sales email. Sales calls have their own rules too; always respect anyone who asks not to be called again.
• Visits and events. Trade fairs, local business associations, industry meetups.
• Content and referrals. Slower, but they bring contacts who already know you.

OpenSells is built for the first case: it finds businesses by industry and city, with their phone number when published, and prepares a brief for each call.

If you send email: how to write one people read

1. A specific subject line. "Partnership proposal" says nothing. Use something that could only be for that company.
2. The first paragraph is about them. Show you looked at their business: a service on their website, their area, something you noticed.
3. Short. What you do, for whom and what you propose, in a few lines that fit on a phone screen.
4. One easy ask. "Would a 15-minute call this week work?" beats "Looking forward to your reply".
5. Identify yourself and offer an opt-out.
6. Follow up sparingly. One or two spaced reminders; if they ask you to stop, stop.

Deliverability: what Gmail requires

Google publishes requirements for senders to Gmail accounts: authenticate your domain (SPF or DKIM, and both plus DMARC above 5,000 messages a day), keep the spam rate below 0.3% and, for bulk marketing, offer one-click unsubscribe.

What to measure

Measure replies, not opens: many email clients preload images, so opens are unreliable. Separate positive replies and compare by campaign and industry, not overall. Our measurement guide explains how. We do not publish "average reply rates": they depend so much on the list, the offer and the industry that any general number misleads.

Where OpenSells fits

OpenSells finds businesses by industry and city and collects their public details: the phone number and, when the company publishes one on its website, an email. We do not verify mailboxes (no SMTP or MX checks), so addresses may be outdated or generic. For leads with an email, AI drafts a message after reading their site; you review it and can send it through your connected Gmail. Having a legal basis to send it is the sender's responsibility.

Try OpenSells free: first month of the Professional plan free, no card; then Professional €39/mo and Agency €89/mo including Spanish VAT (29 USD and 69 USD when paying from Latin America). See pricing and terms. Note that the app interface is currently in Spanish.