Cold email that still works, and how to choose an agency to run it
Short answer
Cold email still works for B2B when it goes to a researched list, from authenticated and warmed-up domains, at a volume that keeps spam complaints low, with a message plainly relevant to the person reading it. A good cold email agency handles the domains, the list, the copy and the replies, follows the mailbox providers' rules and the law, and reports meetings rather than emails sent.
By Jakub Cambor, founder of AI for Marketing, updated
Does cold email still work?
Yes, for B2B, when it is relevant and sent at a modest volume. What stopped working is sending large amounts of generic email, because the big mailbox providers now publish rules for senders and enforce them. A short, specific email to someone whose business you have actually looked at still gets read and answered; a template blasted to a bought list now mostly lands in junk or is refused.
Gmail's rules took effect for all senders in February 2024 and Google says it has been stepping up enforcement since November 2025, including temporary and permanent rejections. Yahoo began enforcing the same standards in February 2024, and Microsoft has rejected mail from high-volume domains that fail its authentication checks since May 2025.[1][2][3][4]
| Requirement | Gmail | Yahoo | Outlook.com |
|---|---|---|---|
| Who it applies to | Every sender, with extra rules from close to 5,000 messages a day to personal Gmail accounts | Every sender, with extra rules for bulk senders | Domains sending more than 5,000 messages a day to Outlook.com, Hotmail and Live addresses |
| Authentication | SPF or DKIM for all; SPF, DKIM and DMARC for bulk senders | SPF or DKIM for all; SPF, DKIM and a DMARC policy of at least p=none for bulk | SPF and DKIM must pass, with DMARC of at least p=none, aligned |
| Spam complaints | Below 0.3%, and ideally below 0.1% | Below 0.3% | Remove invalid addresses regularly to keep complaints down |
| Unsubscribing | One-click unsubscribe and a visible link in marketing mail | One-click unsubscribe, a visible link, and requests honoured within 2 days | A working, clearly visible unsubscribe link |
| Falling short | Stricter enforcement since November 2025, including rejections | Harm to delivery, enforced since February 2024 | Rejection with error 550 5.7.515 since May 2025 |
Sources: Google, Gmail Help: Email sender guidelines; Google, Gmail Help: Email sender guidelines FAQ; Yahoo Sender Hub, Sender best practices; Microsoft Defender for Office 365 Blog, Outlook's new requirements for high-volume senders
Strictly, Google's rules are enforced on mail to personal Gmail accounts, and its FAQ says they do not apply to mail sent to Google Workspace accounts, where many business buyers read their email. Treat them as the floor anyway: a sender that could not pass them is not one to trust with your domain, and Google also notes that bulk sender status, once reached, never expires.[2]
Searches for cold email itself far outnumber searches for an agency to run it, in both the UK and the US.
| Search | UK | US |
|---|---|---|
| cold email | 590 | 3,600 |
| cold email agency | 90 | 880 |
| All of these | 680 | 4,480 |
Monthly Google searches for each phrase, in each country.
Source: Google Ads monthly search volume, via DataForSEO (September 2026)
What does a good cold email agency do?
A good cold email agency runs the whole system, not just the sending: separate domains and mailboxes set up and warmed up, a list researched against your ideal customer and checked for the law, messages written for each group, sending at a pace the domains can carry, replies answered quickly, and a report of meetings and pipeline. It also tells you when cold email is the wrong channel for what you sell.
- 1
Domains
Buy separate sending domains, never your main one, and set up SPF, DKIM and DMARC and the mailboxes.
- 2
Warm-up
Build each mailbox's sending history gradually before any campaign goes out.
- 3
List
Research companies and people against your ideal customer, verify the addresses and check each one is lawful to contact.
- 4
Copy
Write a first line from real research, one clear ask, and a plain way to opt out.
- 5
Send and watch
Send modest volumes per mailbox, watch complaints and bounces, and pause at the first sign of trouble.
- 6
Replies
Answer within hours, book the meeting, log it in the CRM and honour every opt-out.
The law differs on each side of the Atlantic, and a good agency knows both. In the UK, the ICO says the email marketing rule in PECR does not apply to corporate bodies such as limited companies and LLPs, so you can email them without consent, but sole traders and some partnerships are treated as individuals and need it. Either way you must not hide who you are, you must give a valid address to opt out, and the UK GDPR still applies to a named person's work details.[6]
In the US, the FTC says CAN-SPAM covers all commercial email with no exception for business to business. Headers and subject lines must be accurate, the email must say clearly that it is an advertisement and give a valid postal address, and opt-outs must be honoured within 10 business days. Penalties run up to $53,088 for each email that breaks the rules.[7]
This summarises what the regulators publish; it is not legal advice. The ICO also suggests keeping a do-not-email list of businesses that have opted out and screening every new list against it, which is good practice whatever the law requires.[6]
How do you choose one?
Choose a cold email agency by how it protects your domain, where its lists come from, who writes and approves the messages, how it handles replies and what it reports. Walk away from any agency that wants to send from your main domain, cannot say where its data comes from, or promises a reply rate or a number of meetings before it has tested your market.
| Ask | A good answer | A warning sign |
|---|---|---|
| Which domains do you send from? | Separate domains registered for you, authenticated and warmed up first | Your main domain, or theirs shared with other clients |
| Where does the list come from? | Researched against your ideal customer, verified, with a record of the source | A bought list nobody can trace |
| Who writes the emails? | A person using research on each account, with you approving before launch | One template with a first-name merge |
| How many emails a day? | A modest number per mailbox, raised only while complaints stay low | Thousands a day from the first week |
| What do you report? | Replies, meetings held and the pipeline from them | Opens and emails sent |
| Who is responsible if it goes wrong? | Both of you, and they follow PECR and CAN-SPAM | It is your problem, not theirs |
The last question matters more than most buyers realise. The FTC is explicit that you cannot contract away your legal responsibility by hiring another company to send your email: both the business being promoted and the one sending can be held liable.[7]
We do not sell cold email on its own. Outbound that reads like a person wrote it is part of our B2B marketing service when you need pipeline, run beside the landing page, the follow-up and the CRM work that turn a reply into a meeting and a meeting into revenue. The research behind it is the kind of system we built for Allegiance Industries, where each morning's list arrives in the CRM already researched. For the AI side of prospecting, see AI lead generation.
Proof from our own work
41
Automated lead prospecting
Up to 41 companies researched per daily run, 17 data points per lead, and an estimated $9,000 to $10,000 a year saved (the client's own estimate).
Allegiance Industries, a $100M+ facilities company, built by AfM in 2026 with Make.com, Relevance AI, Apollo and Zoho CRM.
Read the case study1,600+
Inbound lead automation
1,600+ leads processed in the peak quarter; follow-up went from 1 to 3+ days to the same day.
Global technology platform (anonymised), in the same engagement as the paid media result: lead capture, enrichment and CRM entry automated. Delivered by Jakub as a freelance consultant before or while founding AfM.
Read the case study
What we do
We run your marketing for you and make it pay for itself.
- First comes a free written breakdown: we look at your site and any numbers you choose to share, with no logins, and show you where the money leaks and the first thing we would fix.
- Then we fix and run the connected commercial journey: the work that earns attention, the pages that turn it into a lead or sale, and the follow-up that creates the next valuable conversion.
- Everything is actively managed and improved, with a weekly report showing what changed and what it made, and you approve everything before it goes out.
- Rolling monthly. No lock-in, cancel any time.
What it is not
- Not a single-channel agency: we do whatever makes you money next, not ads forever or SEO forever.
- Not a junior team on a six-month lock-in: you work with Jakub directly, rolling monthly.
- Not AI left to run on its own: every piece is reviewed by a person and approved by you.
We also build custom automations, such as reporting digests, lead enrichment and routing, and support triage in tools like n8n, Make and Zapier. They are an add-on to the managed service, not a separate offer.
More questions
What reply rate should a cold email campaign get?
Anyone quoting a figure before seeing your market is guessing. Reply rates depend on how well the list fits, how specific the message is and how much the buyer needs what you sell, so set a baseline from the first few hundred well-targeted emails and judge changes against your own numbers.
Should cold email come from our main domain?
No. Use separate domains that look like yours and point to your site, so a bad week for outreach cannot hurt the email your customers and suppliers rely on. Set them up with SPF, DKIM and DMARC and warm them up before they send.
Is cold email to the UK different from the US?
Yes. In the UK the main line is between corporate bodies, which you can email without consent under PECR, and sole traders and some partnerships, which need it. In the US, CAN-SPAM applies to every commercial email but works on opt-outs rather than consent. Both require you to say who you are and give a way to opt out.[6][7]
Related answers
- AI lead generationB2B companies use AI for lead generation in four places: researching which companies and people fit, enriching each lead with verified contact and company data, drafting outreach that refers to something real about the prospect, and routing new enquiries to the right person at once.
- Lead generation agencyLead generation is the work of finding people who might buy from you and getting them to raise their hand: fill in a form, book a call or reply.
- Email marketing agencyAn email marketing agency for an ecommerce brand builds and runs the automated emails that sell while nobody presses send, such as the welcome, abandoned basket, post-purchase, replenishment and win-back flows.
- B2B lead generation and marketingResearched LinkedIn and email outreach, Google campaigns, landing pages and follow-up, judged on the leads sales accepts.
Sources
- 1.Google, Gmail Help: Email sender guidelinessupport.google.com
- 2.Google, Gmail Help: Email sender guidelines FAQsupport.google.com
- 3.Yahoo Sender Hub, Sender best practicessenders.yahooinc.com
- 4.Microsoft Defender for Office 365 Blog, Outlook's new requirements for high-volume senderstechcommunity.microsoft.com
- 5.Google Ads monthly search volume, via DataForSEO (September 2026)dataforseo.com
- 6.Information Commissioner's Office, Business-to-business marketingico.org.uk
- 7.US Federal Trade Commission, CAN-SPAM Act: A Compliance Guide for Businessftc.gov