How to send bulk email without ending up in spam or breaking the law

The usual mistake: BCC from Gmail or Outlook

Sending the same email to a hundred or two hundred people from your normal account causes several problems at once:

• Sending limits. Gmail and Outlook limit how many messages you can send per day and temporarily block your account if you exceed them. You could lose your email just when a client writes to you.
• Spam. A large send from a personal account, with no unsubscribe option, is exactly what filters look for. If several people mark it as spam, your normal emails will start landing in spam too.
• Privacy. All it takes is putting the addresses in “To” instead of “BCC” once, and everyone sees everyone's email. That is already a data protection problem.
• You don't know what happens. You can't see who opened it or who wants to unsubscribe.

Your everyday email is for talking to clients one to one. Writing to many at once needs a tool built for it.

What Gmail and Outlook require today

Since 2024 Gmail has become much stricter with people who send a lot of email, and Outlook followed in May 2025. In short:

Authenticate your domain

Three technical records set up once in your domain's DNS: SPF says which servers may send on your behalf, DKIM signs your messages and DMARC says what to do with emails that fail those checks. Gmail requires SPF or DKIM from every sender, and all three from those sending 5,000 or more messages a day. Outlook also requires them above 5,000 a day and rejects messages that don't comply.

One-click unsubscribe

Marketing emails must allow unsubscribing with a single click, and the request must be honoured quickly.

Few complaints

Gmail recommends keeping the spam rate below 0.10% and never reaching 0.30%. Put another way: if three people in a thousand mark you as spam, you have a problem.

You may not send 5,000 emails a day, but these rules define what filters consider a trustworthy sender. If your domain is set up properly, your normal emails get delivered better too. A good sending tool guides you through the setup.

Source: Gmail, email sender guidelines. Source: Microsoft, Outlook requirements for high-volume senders.

If you don't have email on your domain yet, start here: Business email with your own domain: what it is, benefits and how to choose ↗

What the law says in Spain

This is where many businesses get it wrong without realising. Spain's Information Society Services Act (LSSI) bans sending advertising by email to anyone who has not requested or expressly authorised it. Other EU countries have similar rules. There is one important exception:

• You may write to your clients if they gave you their email when buying from you and you offer them similar products or services of your own.
• Always give them a simple, free way to unsubscribe, both when collecting the address and in every email.
• Everything else needs consent: trade fair contacts, business cards, addresses found online or purchased databases. Buying a list is also the fastest way to wreck your domain's reputation.

The LSSI classes mass sending of commercial emails without meeting these requirements as a serious infringement, with fines from €30,001 to €150,000. On top of that comes the GDPR: you must say who processes the data and why, and store it carefully.

I am not a lawyer: if you have doubts about your specific case, ask a data protection specialist.

Source: Law 34/2002 (LSSI), articles 21, 38 and 39, Spanish Official Gazette (BOE).

And for your website's other legal obligations: website legal pages in Spain: legal notice, privacy and cookies ↗

Which tool to use

An email marketing tool handles sending, unsubscribes and statistics, and helps you set up your domain. Depending on your case:

To start: MailerLite or Brevo

Simple, with free plans for small lists. More than enough for most service businesses.

Mailchimp

The best known. Very complete, but its price rises quickly as your list grows.

Amazon SES with Sendy or listmonk

For technical profiles or large lists: sending through Amazon SES costs cents per thousand emails, but someone has to set up and maintain the technical side. I use Amazon SES for this website's contact form, and it is an excellent option if it is configured properly.

All-in-one platforms

Tools such as ClickFunnels include email, but you would pay much more for features a service business rarely needs. I explain it in ClickFunnels: what it is, what it costs and whether your business needs it.

I compare each option, with current prices, in The best software for sending newsletters (and which to choose) ↗

What to do with the list you already have

If you have been collecting addresses for years, don't import them all into the tool at once:

1. Separate clients from contacts. You may write to clients you have worked with about similar services. Not to the rest without their permission.
2. Clean the list. Remove old, duplicate or defunct-company addresses. Lots of bounces in a row damage your sender reputation.
3. Ask the doubtful ones for permission. One personal email explaining what you will send, with a button to sign up. Anyone who doesn't respond is out.
4. Add a form to your website so new people can sign up themselves. It is the highest-quality list you will ever have.

What to send so people read it

Following the rules keeps you out of trouble, but it doesn't make people read you. That depends on what you write. I have been writing for businesses since 2010, and in email the same things almost always work:

• Be useful before selling. A practical tip, a real case or an answer to a common question gets read; an offer every three months gets ignored.
• Write the way you speak. An email from one person to another, not a brochure full of images.
• One topic and one action per email. Ask for five things and people will do none.
• Consistency. One useful email a month, every month, beats four in a row and then nothing for a year.
• A clear subject line. Say what the email is about, without tricks or capitals.

The basics are in the four principles of copywriting.

Checklist before you press send

• Is everyone on the list a client or someone who has given permission?
• Are you sending from an email tool, not from your mailbox?
• Does your domain have SPF, DKIM and DMARC set up?
• Does the email have a visible unsubscribe link that works?
• Is it clear who is sending and why the person is receiving it?
• Have you sent yourself a test and read it on your phone?

Common questions