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Email deliverability: keep your email out of spam
For anyone who sends to a list: how to set up your domain, how much to send, and how to fix bounces and spam-folder problems.
Since 2024, Gmail and Yahoo have required bulk senders to authenticate their email with SPF, DKIM and DMARC, keep spam complaints low and offer one-click unsubscribe. Microsoft added similar authentication rules for Outlook.com in May 2025. Getting these basics right matters more than any trick. Start with the deliverability checklist, and verify your list with Veml before a big send.
Set up your domain
- For senders
SPF, DKIM and DMARC explained
What each record does in plain English, with examples, alignment, a safe DMARC rollout and the bulk-sender rules.
- For senders
Email deliverability checklist
Everything Gmail, Yahoo and Outlook check before they decide inbox or spam, in one list.
- For senders
Mail tester
How to score your email with mail-tester.com, what the score means, and other free checks before a big send.
- For senders
Email marketing tools
Mailchimp, MailerLite, Brevo, Kit and Constant Contact free plans compared, and how to choose.
- For senders
Product launch email sequence
A 6-email launch sequence with timing, subject lines and a launch-day template.
- For senders
How to write a newsletter
A simple structure, a template, content ideas and subject lines for small business and company newsletters.
- For senders
How to build an email list
Sign-up forms, opt-in offers, permission, and why never to buy a list.
- For senders
Primary domain vs cold email domain
Why outreach usually goes out from a separate domain, how to name it, and how to set it up properly.
- For senders
What is BIMI?
How brands get their logo next to their emails in Gmail, Yahoo and Apple Mail, what it requires, and whether it is worth it.
Sending
- For senders
How many cold emails per day?
Safe daily limits per inbox and per domain, Gmail and Workspace hard limits, and how to ramp up.
- For senders
Email many people without showing addresses
Use Bcc in Gmail and Outlook, the recipient limits, and when to switch to mail merge or a newsletter tool.
- For senders
Subject lines and spam words
What really sends email to spam, the words and habits to avoid, and subject lines that get opened, with before-and-after examples.
- For senders
Email preheader text
What preview text is, how long it should be, and 40 preheader examples and CTA phrases to copy.
- For senders
Subject line capitalization
Title case or sentence case? When each fits, examples side by side, and why ALL CAPS hurts.
- For senders
Emojis in subject lines
Where emojis display, how to use them well, accessibility tips, and examples.
- Email help
Why attachments go to spam
Why emails with attachments are treated as risky, the file types Gmail and Outlook block, and how to send files without landing in spam.
- For senders
What is mail merge?
What a mail merge does, what you need, real examples, and the easiest way to do one.
- For senders
How to mail merge from Excel to Word
Letters, labels and emails from an Excel list with Word’s Mailings tab, plus fixes for dates and ZIP codes.
- For senders
Split an email list into batches
When to split a list, the published Gmail, Workspace and Outlook.com sending limits, and how to split in a spreadsheet.
Bounces and list quality
- For senders
Email bounce-back messages
What "Address not found" and "Delivery has failed" mean, how to read them, and how to fix the cause.
- For senders
Soft bounce vs hard bounce
The difference, the error codes behind each, and exactly what to do with each type.
- For senders
How to clean an email list
A 7-step routine to remove bad, risky and inactive addresses before your next send.
- For senders
Email list hygiene best practices
The habits that keep a list healthy all year: double opt-in, sunset policies, and avoiding spam traps.
- For senders
Clean a Mailchimp audience
Export, tidy, check and archive the bad addresses in Mailchimp, using Mailchimp's real menu names.
- For senders
Clean your list before switching platforms
Moving to a new email tool? Export everything, keep your unsubscribes, match fields and check addresses before the first send.
- For senders
What is a suppression list?
Unsubscribes, bounces and complaints: why you keep them forever and how to remove them from any list.
- For senders
Stop fake and bot signups
Spot bot signups, add double opt-in, a honeypot and a CAPTCHA, and clean out the fakes already on your list.
Background
Technical reference
- For senders
SMTP conversation explained
A real SMTP session line by line: EHLO, STARTTLS, AUTH, MAIL FROM, RCPT TO, DATA and the reply codes in between.
- For senders
Email header fields explained
What every common email header means, from Received and Return-Path to Message-ID, References and List-Unsubscribe.
- For senders
TLS vs STARTTLS
Port 465 vs 587, implicit TLS vs STARTTLS, and why encryption in transit is not the same as end-to-end encryption.
- For senders
Why forwarding breaks SPF and DMARC
Why forwarded mail fails SPF, when DKIM survives, what ARC and SRS do, and how to forward without losing mail.
- For senders
No DMARC record found
What both DMARC warnings mean, how to add a record in minutes, and how to move safely to quarantine and reject.
- For senders
DKIM fail
Why DKIM fails, how to check it is on, and how to set it up in Google Workspace and Microsoft 365.
- For senders
Disable Direct Send
What Direct Send is, why attackers abuse it, and how to turn on Reject Direct Send safely.
- For senders
Email encoding explained
MIME, Base64, quoted-printable and UTF-8: how email carries attachments and special characters, and why garbled text happens.
Questions people ask
- Why do my emails go to spam?
- The usual causes are missing SPF, DKIM or DMARC, sending too much too fast, a list with many bad addresses, or content that looks like spam. The checklist covers each one.
- Do I need DMARC?
- If you send in bulk to Gmail or Yahoo, yes: at least p=none.