SMTP error 530 means: I won’t accept your message until you log in. The server is asking for authentication and your client either didn’t provide credentials, sent the wrong ones, or tried an authentication method the server doesn’t accept on this port. It’s purely a configuration issue, not a deliverability one.
The 530 checklist
| Step | What to verify |
|---|---|
| SMTP username and password | Use the credentials from your Mailpro account — not your email password. |
| Port and security | Use 587 (STARTTLS) or 465 (SSL/TLS). Port 25 without auth is blocked almost everywhere. |
| Authentication method | Most clients need AUTH LOGIN or AUTH PLAIN over TLS. |
| From address | Use a sender that belongs to your authenticated account. |
| Connection from CRM/CMS | Test the connection from the integration before using it in production. |
Where to find your SMTP credentials
Mailpro provides a dedicated SMTP user/password under your account, separate from the web login. Always copy them from the SMTP integration screen, never reuse your email password — that’s the most common cause of 530.
Sending from a CRM or app that demands SMTP auth? Mailpro's authenticated relay handles AUTH LOGIN, SPF, DKIM and DMARC out of the box — start free, no credit card.
Beyond the 530 error
Authenticated SMTP, ready in minutes
Mailpro is an authenticated SMTP relay with SPF, DKIM and DMARC pre-configured. Point your CRM, WordPress site or app at it, drop in your credentials, and the 530 prompt disappears.