Cold email deliverability Cold email deliverability

What is cold email deliverability?

Deliverability is whether your email reaches the inbox, not just the receiving server. A delivered message can still land in spam. Providers decide based on who sent it, how recipients react and what it looks like.

Cold email starts at a disadvantage, because the people you write to didn’t ask to hear from you. Each spam report counts against your domain.

What do SPF, DKIM and DMARC do?

They’re three DNS records that let a receiving server check a message really came from your domain. DMARC ties the other two to the address people see.

What does DMARC alignment mean?

Alignment means the domain that passed SPF or DKIM matches the domain in the From: address. Relaxed alignment accepts the same organizational domain, so mail.example.com aligns with example.com. Strict alignment needs an exact match.

If a sending tool signs mail with its own domain instead of yours, SPF and DKIM can pass while DMARC fails. Ask the provider to sign with your domain, and add its servers to your SPF record.

What do the records look like?

• SPF: v=spf1 include:_spf.example-provider.com ~all. Your email provider gives you the include: value. Ending with ~all marks other senders as a soft fail, and -all as a fail.
• DKIM: your provider generates the key. You publish it at a name like s1._domainkey.example.com.
• DMARC: v=DMARC1; p=none; rua=mailto:dmarc@example.com, published at _dmarc.example.com. Microsoft advises moving from none to quarantine to reject once every legitimate source is aligned.

What do Gmail and Yahoo require from senders?

Google announced its sender rules on October 3, 2023, and both Google and Yahoo began enforcing theirs in February 2024. Gmail’s cover mail to personal Gmail accounts. Yahoo’s cover every domain Yahoo Mail hosts, including AOL.

Microsoft added similar rules for Outlook.com, Hotmail and Live addresses. Since May 5, 2025, domains sending more than 5,000 emails a day must pass SPF and DKIM. They also need a DMARC record of at least p=none that aligns with SPF or DKIM.

Do these rules apply to B2B cold email?

Partly. Google says its requirements don’t apply to mail sent to Google Workspace accounts, only to personal Gmail. Cold email to company addresses falls outside them, even when the company uses Google Workspace.

Meet them anyway. Yahoo and Microsoft ask for the same records, and Google counts all your subdomains toward one bulk-sender total. Google also leaves recipients to decide what’s promotional, so give every cold email a clear opt-out.

Gmail’s guidelines also say not to send messages to people who didn’t sign up for them. Cold email to a personal Gmail address goes against that, so write to work addresses only.

How fast can you increase sending volume?

Neither Google nor Yahoo publishes a safe daily number, so treat any fixed warm-up schedule as a rule of thumb. Here’s what they advise instead:

• Start small and steady. Begin with a low volume to engaged recipients, and send at a consistent rate rather than in bursts.
• Avoid sudden jumps. Google warns that doubling your volume at once can bring rate limiting or a drop in reputation. Yahoo says a spike can get you flagged as a compromised sender.
• Go slower as volume grows. The more you send, the more slowly you should increase. Sending daily lets you increase faster than sending weekly.
• Back off when errors rise. If messages bounce or are deferred, cut volume until the errors drop, then increase slowly again.
• Respect rate limits. Gmail usually answers with error 4.7.28 when you exceed its limits. Stop for at least 10 minutes, then resume on a single connection.

For cold email, a cautious approach is to start each new mailbox with a small daily number. Add volume week by week while bounces and complaints stay low.

What else affects cold email deliverability?

The message

• Keep it plain. Write short emails with few links. Google asks that every link be visible and easy to understand.
• Be honest in headers. Google says not to start a subject with Re: or Fwd: unless the email really is a reply or forward.
• Name yourself clearly. The display name should identify the sender, without emojis, urgency or the recipient’s name.
• Don’t hide content. Google says hiding text with HTML or CSS can get mail marked as spam.
• Accept replies. Microsoft asks for a From: or Reply-To: address that’s valid and can receive mail.

The list

• Write to the right people. Pick contacts with a clear business reason to hear from you; see how to build a B2B prospect list.
• Don’t buy lists. Google and Yahoo both tell senders not to purchase addresses.
• Check addresses first. Use the free email verifier and keep your bounce rate under 2%.
• Honor every opt-out. Remove people who opt out or complain, and never add them back.

The sending setup

Keep cold outreach apart from your company’s everyday mail. Yahoo advises separating mail types by IP or DKIM domain, and Google suggests one From: address per type of message. A subdomain with its own SPF, DKIM and DMARC records keeps them apart.

How do you monitor cold email deliverability?

• Google Postmaster Tools. Add your DKIM (d=) or SPF (Return-Path) domain and verify it in DNS. Dashboards cover spam rate, reputation, authentication, delivery errors and compliance status.
• Its limits. It covers only mail to personal Gmail accounts. Google’s API guide says only domains sending to at least 50 users a day get statistics.
• DMARC reports. The rua address receives aggregate reports showing who sent mail as your domain and whether it passed.
• Yahoo’s Complaint Feedback Loop. Enroll your DKIM domain in Yahoo Sender Hub to get a report each time a Yahoo user marks your mail as spam.
• Your own numbers. Track bounces, replies, opt-outs and SMTP errors. Rising 4.7.x deferrals or 5.7.x rejections usually mean a provider is pushing back on policy grounds.

Don’t judge deliverability by open rates. Google says it doesn’t track them, and that low open rates aren’t necessarily a sign of spam problems.

Last updated September 28, 2026