Agency & Multi-domain
Operational Email Checklist for Web Agencies Managing Client Domains
Same gates every site. Builder leftovers go first.
web agency email checklist
Read the guideMailerZ Blog
Domain email guides you can operate.
Page 3 of 13. Search from the catalog when you need a title, keyword, or topic filter.
25 of 315 articles25 articles per page. New posts join this catalog as they publish.
Security & Abuse
TLS for SMTP: What It Protects and What It Does Not
Hop encryption. Not E2E. Not placement. Leave TLS on.
smtp tls security
Read the guideSMTP Send-as
What Is SMTP Send-As and Why Forwarding Alone Is Not Enough?
MX gets mail in. SMTP send-as gets your domain back out. Gmail replies without SMTP still look like Gmail.
smtp send as
Read the guideTroubleshooting & SMTP Codes
Email Incident Runbook: Missing Custom-Domain Messages
Evidence before DNS. You cannot recover mail that hit another host.
missing email incident runbook
Read the guideEmail Forwarding Fundamentals
Can You Forward Email Without Hosting a Mailbox?
Forwarding is a hop. Hosting is a login. You still publish MX. You do not owe IMAP on the domain.
email forwarding without mailbox hosting
Read the guideDeveloper & Website SMTP
How to Diagnose WordPress 'Could Not Authenticate' SMTP Errors
AUTH failed is credentials or plan, not a Gmail tab. Free cannot send-as.
wordpress smtp authentication error
Read the guideCost & Workspace Alternatives
Mailbox Seat vs Email Alias Cost: A 10-Person Team Example
Ten people often need ten existing inboxes plus a handful of role aliases. Buy suite seats for stores you will open. Do not buy a mailbox per printed name.
email alias vs mailbox cost
Read the guideDeliverability & Spam
Gmail Spam Filters and Forwarded Mail: What You Can and Cannot Control
gmail forwarded mail spam filter: one MX set, leftover hosts gone, Gmail or Outlook as the store.
gmail forwarded mail spam filter
Read the guideSecurity & Abuse
Why Open Relays Are Dangerous and How Verified Sending Prevents Them
Client, not server. AUTH plus mapped From. Close inbound 25.
open relay email security
Read the guideEmail Aliases
Custom Domain Email Alias: How It Works Without Another Inbox
One store. Many names. MX plus a map. Not another mailbox product.
custom domain email alias
Read the guideDeliverability & Spam
How to Diagnose Gmail 'Message Blocked' After Forwarding
gmail message blocked forwarding: one MX set, leftover hosts gone, Gmail or Outlook as the store.
gmail message blocked forwarding
Read the guideDNS Provider Guides
Route 53 MX Record Priority and Formatting Explained
Priority is order. Demoting is not deletion. Hostnames not IPs.
route 53 mx priority
Read the guideDNS & MX
Why Mixed Google and Custom MX Records Cause Random Delivery
Two MX products is a coin flip. History only sees the MailerZ half. Unmix. Then probe.
mixed mx records google
Read the guideCustom Domain + Gmail
How to Create support@, sales@ and billing@ Without Extra Gmail Accounts
Role addresses are routes, not seats. Map three names. Cut leftover MX. Probe from another mailbox.
domain aliases without extra gmail accounts
Read the guideCompetitor Comparisons
MailerZ vs Purelymail: Routing Layer vs Low-Cost Mail Hosting
Name the store. Quote $10 live. Keep Gmail and add a hop, or move IMAP. Not both MX.
mailerz vs purelymail
Read the guideAgency & Multi-domain
How to Avoid Shared SMTP Credentials Across Clients
One user per zone. Rotate on offboard. A shared .env is every client’s incident.
smtp credentials per client
Read the guideEmail Forwarding Fundamentals
Free Email Forwarding vs Paid Forwarding: Where the Risks Actually Are
Free proves inbound on one domain. Paid adds send-as, a 90-day store, and optional catch-all forward. Price does not fix leftover MX or inbox tabs.
free vs paid email forwarding
Read the guideCompetitor Comparisons
MailerZ vs Fastmail: Forwarding Layer vs Hosted Mailbox
Fastmail is a store. MailerZ is a hop. Keep Gmail and add MailerZ, or move the store to Fastmail. Not both MX.
mailerz vs fastmail
Read the guideCompetitor Comparisons
MailerZ vs Microsoft 365: When You Do Not Need Another Mailbox Seat
Need Calendar and a hosted mailbox? Buy 365. Need hello@ into an inbox you have? Buy a hop.
mailerz vs microsoft 365
Read the guideDeliverability & Spam
What “Delivered” Means in SMTP—and What It Does Not Mean
250 is acceptance. Search the store after. 4xx retries. 5xx stops. Sent folder is not inbound.
smtp delivered meaning
Read the guideDNS & MX
Email DNS Cutover Runbook for Small Businesses
Aliases before the window. Exclusive MX during it. Third-mailbox proof. Rollback is the old screenshot, not dual MX.
email dns cutover runbook
Read the guideDeveloper & Website SMTP
WP Mail SMTP Alternative Setup With a Custom SMTP Relay
Paid dashboard SMTP, mapped From, one unique test. Free cannot send-as.
wordpress smtp relay setup
Read the guideMigrations
Email Provider Migration Checklist: DNS, Aliases, SMTP and Rollback
Four objects: DNS, aliases, SMTP, rollback. Cut inbound once. Move SMTP after inbound proof. Cancel last.
email provider migration checklist
Read the guideCustom Domain + Gmail
How to Forward Your Domain Email to Gmail and Keep the Original Sender
The sender people see is a header. A From rewrite breaks authentication. Cut leftover MX. Probe from another mailbox.
forward domain email to gmail
Read the guideAgency & Multi-domain
Multi-Domain SMTP Sending Without Running Your Own Mail Cluster
You do not need Postfix on a VPS. You need approved Froms and a lookup-safe SPF per zone.
multi domain smtp sending
Read the guide