Email deliverability for a small business

Whether your email reaches the inbox depends mostly on 3 things you control: proving the mail really comes from you, sending only to people who want it, and making it easy to stop. The big mailbox providers now write these down as rules, and mail that ignores them is filtered or turned away.

This guide explains what Gmail, Yahoo, and Outlook ask of senders, how to tighten DMARC without blocking your own mail, what the US CAN-SPAM Act requires, and a short checklist for an accountant, a law office, or any small business that relies on email to reach clients.

Delivered is not the same as seen

An email can be accepted by the receiving server and still land in the spam folder, where nobody reads it. Deliverability is the share of your mail that reaches the inbox. Your sending tool may report a message as delivered when the client never saw it.

The usual sign is a client saying "I never got it" about an invoice, a document request, or a booking confirmation. If you hear that more than once a month, the problem is probably your setup, not your client's inbox.

What Gmail, Yahoo, and Outlook ask of every sender

Since February 1, 2024, Google has asked everyone who sends to Gmail accounts to authenticate their mail with SPF or DKIM, keep valid DNS records for their sending servers, send over an encrypted connection, and keep spam rates below 0.3%.^[1] Yahoo's rules for all senders are much the same, including SPF or DKIM and a spam rate below 0.3%.^[2]

Three terms do most of the work here. In plain words, they are records you publish on your domain name.

• SPF lists the servers allowed to send email for your domain.
• DKIM adds a signature to each email so the receiver can check it was not changed and came from your domain.
• DMARC tells receivers what to do when a message fails those checks, and sends you reports about mail using your name.

The stricter rules for bulk senders

Google applies extra rules to senders of more than 5,000 messages a day to Gmail accounts.^[1] Microsoft followed with the same line for Outlook.com, Hotmail.com, and Live.com addresses from May 5, 2025. Its announcement says non-compliant mail goes to junk at first and can then be rejected outright.^[4] Yahoo applies bulk rules too, without publishing a number.^[2]

The table draws on Google's sender guidelines,^[1] Yahoo's sender best practices,^[2] and Microsoft's announcement.^[4] If your list has Gmail, Yahoo, and Outlook.com addresses on it, as most client lists do, meet the strictest entry in each row.

Most small businesses never send 5,000 emails in a day. As an illustration, not data from a real firm: an accounting practice with a 6,000-person newsletter list crosses that line the day it sends to everyone. Set up all of it anyway. It costs nothing extra, and it protects your domain from people sending fake mail in your name.

Tighten DMARC in 3 steps

The DMARC standard defines 3 policies. At p=none you ask receivers to take no special action and to send you reports. At p=quarantine you ask them to treat failing mail as suspicious. At p=reject you ask them to refuse it.^[5] Jumping straight to reject can block your own invoices, so move in stages.

1. Start at p=none with a reporting address, so the reports show every service sending mail in your name, such as your booking tool, accounting software, and newsletter.
2. Fix each legitimate sender that fails, by adding it to SPF or turning on DKIM for it.
3. Move to p=quarantine, then p=reject, once a month of reports shows only your own services. That is the step that stops strangers sending fake invoices from your domain.

Most firms do not manage their own DNS. Here is a request to copy and send to whoever does.

"Hi, could you check our domain's email records this week? Please confirm we have an SPF record listing every service that sends mail for us, DKIM turned on for each one, and a DMARC record at p=none with reports going to an address we read. Send me the list of services you find, and we will review the reports in a month before tightening the policy."

Watch your spam complaint rate

Google asks senders to keep the spam rate shown in its free Postmaster Tools below 0.10%, and never to reach 0.30% or higher.^[1] That is 1 complaint per 1,000 messages as a target, and 3 per 1,000 as the line not to cross.

A complaint is a person clicking "Report spam". People do that when they do not remember signing up, when mail arrives far more often than they expected, or when unsubscribing looks hard. All 3 are fixable.

Send from your own domain

Mail from a free personal address or a shared sending domain borrows someone else's reputation. Inbox providers trust mail that comes from a domain you own. With your own sending domain, reminders, invoices, and newsletters go out from your practice's web address, and we connect the records during setup.

Larger senders can add a private sending server, an optional add-on with its own monthly price, so no other sender affects their reputation. Our team checks the email delivery dashboard as part of ongoing account health checks. Emails cost $2.03 per 1,000 at published rates.

The CAN-SPAM basics

This section is general information, not legal advice. If email marketing is a large part of your business, ask a lawyer to review your process.

The Federal Trade Commission's compliance guide sets out the main requirements for commercial email. Do not use false or misleading header information or deceptive subject lines. Identify the message as an ad, include your valid physical postal address, tell people how to opt out, and honor opt-outs within 10 business days.^[3]

The guide says each separate email in violation can bring penalties of up to $53,088, and that the law makes no exception for business-to-business email.^[3] It also describes transactional or relationship messages, such as confirming a transaction the client already agreed to, and treats those differently from marketing.^[3] Mixed messages need care, so keep invoices and reminders free of promotions.

The 10-day legal limit is the outer edge. Yahoo asks bulk senders to honor unsubscribes within 2 days.^[2] The safe habit is to remove people straight away.

A checklist for this month

1. Check that your domain has SPF, DKIM, and DMARC records. Your IT contact or our team can confirm it in a few minutes.
2. Send client email from your own domain, not a free personal address.
3. Only email people who gave you their address and expect to hear from you. Do not buy lists.
4. Put a visible unsubscribe link in every marketing email, and make sure it works in one step.
5. Remove addresses that bounce, and stop mailing people who have not opened anything in a long time.
6. Keep invoices, document requests, and reminders separate from newsletters and offers.
7. Look at your delivery and complaint numbers once a month.

Professional firms depend on clients receiving engagement letters, tax document requests, and invoices on time. See how a professional services firm runs client email, reminders, and billing from one account. If you text clients too, our guide to business texting registration covers the carrier side.

Not sure your email is set up correctly? Book a walkthrough and we will check your domain records with you, or compare plans.