What does “550 Sender verify failed” mean? #

Many mail systems perform sender verification as an anti-spam measure. If the server can’t confirm the sender address is valid,
it rejects the message with a 550 error.

Most common causes on hosting #

• The sender email account does not exist in cPanel (example: you’re sending as
  [email protected] but that mailbox was never created).
• Email Routing / MX mismatch: your domain’s DNS MX points to an external provider (like Google/Microsoft),
  but cPanel still expects local email delivery (or vice versa).
• Website forms spoofing “From”: contact forms often set “From” to the visitor’s email (which isn’t a real mailbox on your domain),
  causing verification failure.
• Wrong SMTP login: you’re authenticating with one mailbox but trying to send as a different address.

Fix #1: Confirm the sender mailbox exists in cPanel #

First, verify the email address you’re sending from actually exists as a mailbox on the server. This is the #1 fix.

1. Log in to cPanel.
2. Go to Email Accounts.
3. Check whether the mailbox (sender address) exists.
4. If it doesn’t exist, create it, then resend.

Fix #2: Set the correct Email Routing (Local vs Remote Mail Exchanger) #

cPanel uses Email Routing to decide where mail for a domain should be delivered.

If your email is hosted on Hosticko (local email) #

1. cPanel → Email Routing
2. Select your domain
3. Choose Local Mail Exchanger
4. Click Change

“Local” is used when the server itself is responsible for mailboxes and delivery for that domain.

If your email is hosted elsewhere (Google Workspace / Microsoft 365 / other provider) #

1. cPanel → Email Routing
2. Select your domain
3. Choose Remote Mail Exchanger
4. Click Change

“Remote” is used when your MX records point to an external provider (so the server should not try to deliver locally).

Fix #3: Verify MX records match your email provider #

Your MX records must match where you want to receive email. If MX points to Google but cPanel is set to Local,
you’ll get weird issues (including sender verification failures in certain setups).

1. Open cPanel → Zone Editor.
2. Click Manage for your domain.
3. Review your MX entries (remove old/conflicting ones).
4. Make sure they match your intended email provider.

Fix #4: If this happens on WordPress contact forms #

This is super common: the form plugin sets the “From” address as the visitor’s email (not a real mailbox on your domain),
and the server rejects it.

• Set the From address to a real mailbox you own (example: [email protected]).
• Put the visitor’s email in Reply-To instead (so you can reply to them easily).
• Use SMTP (plugin like WP Mail SMTP) authenticated with that same mailbox.

Quick checklist (90-second diagnosis) #

• ✅ Is the sender mailbox created in cPanel? :contentReference[oaicite:8]{index=8}
• ✅ Are you using the correct SMTP username/password for that mailbox?
• ✅ Does Email Routing match your MX setup (Local for Hosticko mail / Remote for external provider)?
• ✅ Are your website forms using a valid “From” address (not spoofed)?

FAQs #

Why does this happen even though my domain email “exists”? #

Sometimes the mailbox exists at an external provider (like Google Workspace), but cPanel is still configured for local delivery.
Set Email Routing to Remote Mail Exchanger when MX points externally.

What if I’m sending from an app or website script? #

Make sure the app uses SMTP auth with a real mailbox (and that the “From” address matches that authenticated mailbox).
Avoid spoofing random sender addresses.

Do I need to change anything if I use parked/addon domains? #

Yes, each domain’s routing/MX must match its email provider, especially when you add addon/parked domains under the same account.