How email really works, told in short reads.

Subscriptions

The 30-day renewal reminder: what a small app emails customers before charging them for another year

A practical 30-day reminder gives customers time to review an annual renewal, update their card, or cancel. Here is a short checklist and a template you can adapt.

Authentication

We checked BIMI across 100 top domains: 38 have a VMC certificate, 10 host an SVG Gmail ignores

Can you get your brand logo in inboxes without paying $1,500 a year for a certificate? We checked 100 top email domains: 38 paid for a Verified Mark Certificate, 10 published an SVG that only Yahoo shows, and 3 published empty records. What BIMI really requires.

AI compliance

How an Automated AI Check Reads Every Email: Safety Without Latency

email59 is one of the first email services to combine instant rule-based filters with an automated AI compliance check. Here is how background AI audits work and what happens if an account is held.

Send policy

Why email59 Refuses Marketing Email: Transactional Only, No Promotions

email59 is one of the first email services that completely refuses marketing email. Here is why marketing is blocked, the exact phrases that trigger a refusal, and how transactional mail stays fast.

Kid-safe email

Kid-Safe Email for Families and Schools: What Gets Filtered and What Stays

email59 is one of the first email services with kid-safe mail built in by default. Here is how profanity and foreign scripts are removed, how files are checked, and how families and schools stay safe.

Small business email

We had a data breach: the email a small business owes its customers, and how many days it has

There is no single US deadline: California, Florida, New York and Washington cap many notices at 30 days, Ohio at 45 and Texas at 60, while GDPR gives the regulator 72 hours and people a different clock. Here is the triage table, the six facts the email needs and a template that says only what you know.

Authentication

SPF allows 10 lookups. We counted what 18 email services use: Google 1, Freshdesk 7

How many of SPF's 10 DNS lookups does one email tool spend? We counted 18 services from live DNS and 175 busy domains. Google Workspace now costs 1, not the 4 older guides give, Freshdesk 7. What going over really does, and how to get back under.

Shop emails

Closed for the holidays: the last-order-date email a small shop sends in December

The carriers' Christmas 2026 dates (USPS 17 to 19 Dec, FedEx Ground 15 to 23 Dec by transit days, Royal Mail 18 to 23 Dec), the sum that turns them into your own order-by dates, what the email lists, the two sends (2 December and the last standard day) and who you may send it to.

Small business email

Gmail filters for a one-person business: invoices, orders and notifications sorted as they arrive

Five Gmail filters with the exact searches (from:, subject:, has:attachment, list:), which may skip the inbox and which never should, labels instead of folders, the limits (1,000 filters, 10,000 labels, one label per filter), an XML file to import all five, and what filters can't do: no scheduling, no old mail.

Small business email

Our bank details have changed: the invoice-fraud email that costs small businesses most, and the call that stops it

Business email compromise in FBI numbers (24,768 complaints and $3.05 billion lost in 2025, $123,005 per complaint), the three forms (changed bank details, the boss and the gift cards, the fake invoice from a real supplier), what the headers show and can't, the phone-back rule, and the first hour after paying: 58% of money was frozen when the FBI's kill chain started in time.

Deliverability

We read the DMARC record of the 100 busiest domains that take email: 57 reject fakes, 13 only watch

Reject, quarantine or none? We checked the DMARC, SPF and DKIM records of the 100 busiest domains that take email. 57 refuse fakes, 16 send them to spam, 13 (outlook.com among them) only watch and 14 have no record. The table, what the big ones agree on, and where a small domain should start.

The email59 app

The email59 app or Outlook on your phone: an honest comparison

Outlook's phone app has 9.4M ratings on the App Store, reads many providers and does calendar and files too. The email59 app is new, doesn't read Outlook mail yet, and does one thing: your mailboxes in one feed with an urgent count you can switch on. Who should use which, and what we don't claim.

The email59 app

The email59 app or the Zoho Mail app: which one for Zoho mail on your phone

Zoho's own app rates 4.5 to 4.6 in both stores and does far more than mail. The email59 app does one thing: Zoho next to your other mailboxes in one feed, with an urgent count you can switch on. What each one is for, the Zoho settings email59 needs, and what we don't claim.

The email59 app

Leaving AWS WorkMail before 31 March 2027, without losing mail on your phone

AWS ends WorkMail on 31 March 2027 and has taken no new customers since 30 April 2026. What AWS suggests instead, the two ways to get the mail out (IMAP copy or the export API, which leaves contacts and tasks behind), the order of the switch, and how to keep reading mail on your phone while both mailboxes exist.

Shop emails

The refund email: how much, to which card, and why it takes 5 to 10 days to show up

What a refund email states (amount, the card's last four, the date issued, the dates the bank will show it), Stripe, Shopify, Square and PayPal refund timings in a table, the fee kept on an $80 order ($2.62 on Stripe, $3.28 on PayPal), the ARN for "where's my refund?", and what to send when a refund comes back.

The email59 app

Google Play won't list a new app until these seven things exist (2026)

Privacy policy URL, a web page for account deletion plus a way inside the app, Android 16 (API 36) since 31 August 2026, an app bundle, a support contact, and for new personal accounts 12 testers for 14 days. With dates, sources, a worked timeline and which tool covers each one.

The email59 app

Most of a mail app isn't the mail: who's building the other parts of the email59 app

The email59 app puts Zoho, WorkMail, Outlook and email59 inboxes in one feed on Android. The code is written with Claude Code; sign-in comes from osec.one, Android builds and test installs from aipps.dev, and the store pages from AppBro. What each one covers, what it saved, and what still needs a person.

Account emails

We've updated our privacy policy: when a small app must send that email, and what goes in it

Which privacy policy changes need an email and which only need a new date (EU WP260's three changes that always count), the notice big services give (GitHub 30 days, Microsoft 62), the three lines the email carries, why it goes to newsletter opt-outs too, what the FTC says about retroactive changes, and the send dates worked out for 4,000 accounts.

Small business email

The invoice email that gets paid: PDF or link, the due date in the subject, and the reminder at seven days

What an invoice email carries, a PDF or a pay link (79.6% against 56.1% paid in 3.75 million invoices), how late net 15 and net 30 invoices really get paid, four reminders with dates and wording, and UK late payment interest worked out: 11.75% plus a £70 fixed sum on a £2,400 invoice.

Small business email

Asking for a review by email: the one after delivery, and what the FTC says you can't offer for it

When to ask for a review (about a week after delivery, with response rates by timing), one question and one link straight to the review form, the FTC's 2024 consumer review rule (rewards, gating, hiding bad reviews), Google, Amazon and Etsy rules, and one follow-up at most.

Account emails

Prices are going up: the price-change email a small app sends, and the notice it owes subscribers

When the price-change notice must arrive (California 7 to 30 days, New York 5 business days to 30, Apple and Google Play rules, EU and UK right to cancel), the old and new price and the date in the first lines, keep, switch or cancel links, grandfathering, the reminder a week before, and a worked annual plan.

Gmail

A forward you didn't set: checking Gmail for hidden forwarding, filters and connected apps after a scare

After a phishing click or a lost laptop, a new password doesn't remove a forward, a filter, a delegate or a connected app. Seven places to check in Gmail settings and on the Google Account security page in about ten minutes, what a hidden filter looks like, and what to change, in order.

Small business email

The abandoned-cart email: one reminder, at the right hour, and what a small shop may send without consent

When the cart reminder goes (1 to 4 hours, then once at 24 hours), what it shows (the item, the price, one link back to the cart), Klaviyo and Baymard figures with a worked month, why one or two and not five, and the consent rules in the US (CAN-SPAM), UK (PECR soft opt-in), EU and Canada.

Gmail

Undo Send and recall: what Gmail's 30 seconds can take back, and what Outlook's recall really does

Undo Send holds an email for 5 to 30 seconds before it leaves (Gmail, Apple Mail, Outlook.com, Proton, Zoho); Outlook's Recall deletes a delivered email only inside one Microsoft 365 organisation. Settings for each, what to send when it's too late, and the ICO's steps when personal data went to the wrong person.

Account emails

Trial-ending reminder emails: warning before the first charge without it feeling like a trap

When to send the trial reminder (7 days before fits Visa, Mastercard and the California, New York, Minnesota and Virginia windows), the date and amount in the first line, what happens if they do nothing, one-click cancel, the email when the trial ends, and where the US and UK rules stand in October 2026.

Small business email

The out-of-office reply: what it should say, and why it should not answer every newsletter

What an out-of-office reply says (back on a date, who to contact, nothing about an empty house), how often Gmail and Outlook reply to the same sender, why they shouldn't answer lists and no-reply senders (RFC 3834, Auto-Submitted, Precedence), auto-reply loops, and setting it up in Gmail and Outlook.

Small business email

Email signatures for a small business: four lines, and the logo that arrives as an attachment

What a small business signature needs (name, role, business, one phone or link), what to leave out, why a pasted logo turns into an attachment or a blocked image and how to host it instead, sizes, plain-text fallback, signatures on replies and phones, a shared address, and what UK and German law require in a business email.

Shop emails

Shipping emails for a small shop: the order-shipped email, and the one when a parcel goes wrong

What a small shop's shipped email carries (the items, the carrier, a tracking link that opens on a phone, the expected day as a date), tracking link formats for eight carriers, split parcels, and the delayed, held and returned-to-sender emails, with the FTC and UK rules behind them.

Gmail

'Be careful with this message': what Gmail's warning banners mean and which ones to act on

Gmail's red, yellow and grey banners, word for word: what sets each one off, when it is a false alarm, what to press (Report phishing, never the link), how to read SPF, DKIM and DMARC in Show original, and what a sender can fix.

Account emails

The password reset email: one link, a short life, and the same answer for every address

A password reset flow for a small app: a 256-bit token stored as a hash, used once, alive 30 to 60 minutes, the same answer for every address, the email to an address with no account, sessions ended after the change. With Laravel, Supabase, Devise and Django defaults.

Small business email

One email to 40 people without showing everyone's address: Bcc, mail merge or a list

Cc on a group email has cost UK senders £10,000 to £350,000 in fines. When Bcc is enough, its limits in Gmail and Outlook, mail merge for one email each, and when a club or small business needs a proper list with an unsubscribe link.

Small business email

Leaving your old Gmail for a business address without losing mail

Moving a business from a personal Gmail to a proper address in four stages: the accounts to change first, telling customers without a blast, the auto-reply and forwarding and their limits, and why the old Gmail stays open for a year.

Gmail cleanup

Deleted it by mistake: getting an email back from Gmail's Trash, and what happens after 30 days

Deleted Gmail sits in Trash for 30 days. How to find it with in:trash and in:anywhere, put it back, the buttons that skip the 30 days, Spam's own clock, and what a Workspace admin can still restore after that.

Small business email

One address, two people: running a shared business inbox without answering twice

Forwarding, one shared login, or shared access with your own sign-ins: what each setup does to 'who replied?', the habits that stop double replies, and what to change when someone leaves.

App emails

Export-ready emails: sending a link to a big file instead of the file

Why the export email carries a link, not an attachment: size limits, scanners and forwarding. A link that needs a sign-in or a one-time token, the expiry as a date, what the email says about the file, and the email when the export failed.

Small business email

The contact form that emails you: making website messages arrive, and keeping the junk out

A form email 'from' the visitor fails for Yahoo, AOL and iCloud addresses. Put your own sending address in From and the visitor in Reply-To, what the message should carry, honeypots instead of puzzles, and the monthly test.

Small business email

The booking confirmation email: date, time zone, a calendar file and the way to cancel

What a booking confirmation must carry: what, when with the time zone spelled out, where or the call link, who. The .ics file and add-to-calendar links and their quirks, cancel links that work without a sign-in, the reminder, and the email when you cancel.

Gmail

Primary, Promotions, Social, Updates: who sorts your Gmail, and how to move a sender for good

Gmail's inbox tabs are labels, not folders. What each tab is meant to hold, dragging one email versus moving a sender for good, switching the tabs off, and the search that clears a whole tab.

Sign-up

One mailbox, many addresses: Gmail's dots and plus signs, and what your sign-up form should do about them

Gmail ignores dots and delivers name+anything@ to the same mailbox, so one person can claim a free trial a hundred times. When to treat the addresses as one, why you never rewrite the address you send to, and a comparison key in JavaScript and Python.

Gmail

Archive is not delete: where archived Gmail goes, and why it still fills your storage

Archive only takes the Inbox label off. The email stays in All Mail and keeps counting against your 15 GB. How to find archived mail, the phone swipe that archives by default, and when archiving is right.

Account emails

Account deletion emails: what a small app sends before, during and after someone leaves

Account deletion in a small app takes three emails at most: a confirmation before anything is removed, one date and one undo link in the grace period, and a last email once it's done. Plus what happens to the address on your stop lists.

Account emails

The welcome email has one job

The first email after sign-up should get the person to the first thing they came to do. What goes in, what to leave for later, when to skip it, and the rule that keeps it out of the promotions pile.

Account emails

The receipt email: what a small app's payment receipt has to carry

A receipt is the email people keep on purpose and read again months later. The seven parts it needs, what UK and EU VAT rules add, what never goes in, and how to send it exactly once.

Sign-up

gmial.com: catching the mistyped email address before the first email goes astray

Some typo domains bounce your sign-in code, some swallow it, and some deliver it to a stranger, and a mail server check passes those. How to catch the slip with a short list and a "Did you mean" line.

Links

How click tracking changes the links in an app's email

Click tracking swaps every link for a redirect through the sending service. Why that suits a newsletter better than a password reset, how to turn it off per message, and how to check what your emails arrive with.

Account emails

Was this you? The new-device and password-changed emails people actually read

The emails an app sends after a sign-in from a new device or a changed password. What goes in the subject, which details help and which mislead, the one link, and why they are never optional.

Gmail cleanup

15 GB, three apps: finding out whether Gmail, Drive or Photos filled your Google storage

One 15 GB allowance is shared by Gmail, Drive and Photos, and the warning doesn't say which one used it. How to read Google's storage page, what counts and what doesn't, and what to clear first.

Gmail cleanup

A Google app password: what it opens, what it can't, and how to cancel one

An app password is 16 letters that let a mail app into your Gmail without your real password. What it reaches, what it can't touch, the two Google pages you need, and how to switch one off.

Gmail cleanup

Delete, unsubscribe or filter: which one stops the next email

Three buttons in Gmail that people use as if they were one. Delete clears what is there, unsubscribe asks the sender to stop, a filter makes Gmail deal with it. When each is the right one.

Account emails

The invitation email: when your app writes to someone on another person's word

Invite-a-teammate is the one email an app sends to a person who never gave it their address. Whose name goes where, what the invited person needs to see, how the link should behave, and the limits that keep the feature from becoming someone's spam tool.

Writing email

Every HTML email needs a plain-text twin

An app's email can carry two bodies: HTML and plain text. Who ends up reading the text one, what a stripped-tags version does to a sign-in link, and how to write the text part by hand in ten minutes.

Servers

Your VPS can't send email, and it isn't your fault: port 25, tested on our own server

Most cloud hosts quietly drop outbound mail. We tested ports 25, 465, 587, 2525 and 443 from our own server and a home line. What is blocked where, and three ways to send anyway.

Bounces

A bounce is a to-do item: hard and soft bounces, and when to stop mailing an address

Every bounce is a receiving server telling you something in three digits. What 4xx and 5xx mean for an app's sign-up and notice emails, when to wait, when to stop for good, and why mailing dead addresses costs more than the email.

Account emails

Changing an account's email without handing the account away

The email on an account resets every other key it has. A change-email form that switches it in one step is the quietest way to lose an account. The flow in six steps, the two emails, and what each one says.

Replies

Reply-to on a no-reply sender: where replies to your app's email should go

People press Reply on receipts, alerts and sign-in codes whether you invite it or not. Three addresses decide where that reply lands, four ways to handle it, and which one fits which email.

Gmail cleanup

Gmail storage full? Three kinds of old email you can delete without opening one

A full Gmail is mostly mail nobody reopens: old social notifications, delivery notices and no-reply mail. How to find and clear them by hand with Gmail searches, or in three steps with email59's Gmail cleanup.

Getting started

Email codes for your app in two API calls

One call gets a key, one call sends the code. We ran both and show what came back, the email as it arrived, what you give up by skipping the domain setup, and when to take the longer road.

Sign-up abuse

Someone is signing up strangers to your app: email bombing through sign-up forms

Your sign-up form emails any address typed into it, so it can be used to bury someone else's inbox. Why per-IP limits miss it, and the four checks that take your app out of the attack.

Development

Test emails that never reach a real person: catching mail in development

Sooner or later a staging server emails real customers. Three fences that stop it: a local catch-all inbox, an allowlist in one send function, and test addresses that can't belong to anyone.

Billing emails

The missed-payment email: what to say so people actually update their card

Most people whose payment failed never decided to leave. Their card expired. When to write, what to say, and the one link that gets it fixed, without guilt and without turning a notice into an advert.

Sign-in codes

Six digits, ten minutes: what a sign-in code email needs to get typed in

It's the one email people sit and wait for. How long the code is, how long it lives, how many guesses it allows and where it sits in the message decide whether they get in.

Sign-in links

Your magic link was clicked before your user saw it

A sign-in link that works for every Gmail tester and fails for the first customer at a bank. It isn't your expiry timer. A security scanner opened it first.

Supabase

Supabase stops at 2 emails an hour. Here's what's going on, and the quickest way past it

Your fourth sign-up gets "email rate limit exceeded". That's the built-in sender doing exactly what it says. Two ways out, one of them a short Edge Function.

Choosing a sender

SendGrid's free plan is gone. What a small app can use for sign-up emails now

The 100-a-day plan that powered a decade of side projects became a 60-day trial. Here is what is left, and what each option asks of you.

Sign-up hygiene

Blocking throwaway emails at sign-up, without maintaining a list yourself

Disposable inboxes cost you free-tier abuse and dead newsletter addresses. Here is how to stop most of them in one request, and where to stop trying.

Self-hosting

Why nobody can run their own mail server anymore (almost)

In the late nineties it was a weekend project. Today one bad neighbour on a shared IP address can end it.

Deliverability

Why good email still lands in spam

Usually it is not the words. It is the sender, the links and the people who press the spam button.

Countries

Which countries write the most email? The numbers are rougher than you think

One country tops the per-person charts, another tops the totals, and the sources don't agree on either.

Costs

What 100,000 emails really cost across providers

The bill for 100,000 emails a month at six providers, from $10 to $126, with the plan, the overage and the extras behind each number. List prices checked on 20 October 2026.

Categories

Transactional or marketing? The line that changes how your email is treated

A password reset and a sale announcement can come from the same app and still follow different rules.

Consent

The unsubscribe link: the one button every newsletter is supposed to have

Why it exists, what the rules say in the big markets, and why hiding it costs more than keeping it.

Deliverability

The secret lists that decide whether your email exists

Your message can be perfect and still never reach an inbox, because of a list you have never heard of.

Authentication

SPF: the guest list for every server that claims to speak for you

One DNS line decides whether a stranger can send mail in your name. Five things to know before you touch it.

Software

Spam filters you install, subscribe to, or never see

Free open-source engines, per-user cloud add-ons, and the filter already sitting in the inbox you use.

Protocols

SMTP is from 1982. Why more apps now send email over HTTPS

A protocol built for relays between trusted servers is a poor fit for a web app that needs a message sent in one request.

Hardware

Spam filters you can rack in a data centre, and what they cost

Three appliance families, their list prices, and why the bill is never just the box.

Rules

Gmail and Yahoo changed the rules in 2024. Here is what they require

Five thousand emails a day is the line. Above it, authentication and one-click unsubscribe stop being optional.

History

Email is older than the web. Here are nine frames of how it changed.

It began as a way for two programmers to leave each other a note on a shared machine. Then everything happened.

Authentication

DMARC: the rule that tells mailbox providers what to do with fakes

Three policies, one report address, and why spoofers tend to go quiet once you publish it.

Authentication

DKIM: the wax seal that travels with your message

A signature no one can forge without your private key, and why it breaks when a mailing list edits your mail.

Agents

Bots need an inbox too. How an agent signs in with a code

No password, no browser, no human in the loop. An email code is the oldest trick that still works for software.

Volume

About 390 billion emails a day. Where do they all go?

Roughly 48 for every person on Earth, every single day. A large share of them is machine-made.

Providers

A handful of companies sit in front of most of the world's inboxes

Gmail, Outlook and Yahoo decide, in milliseconds, what you see first. Here is how much they handle.