SMTP Servers
Introduction
Lucy supports sending campaign emails through an external SMTP relay—either via credentials or OAuth2 (Azure). Using a familiar company domain improves email deliverability and trust.
Setup
Navigate to Settings > Common System Settings > SMTP Servers
Select "+ Add Server"
Next, you will define the SMTP Mail Server parameters:
Name
Friendly identifier for selection in Lucy
Client
Optional—restricts server to a specific client
Host & Port
Example: smtp.office365.com, port 587
Encryption
STARTTLS (recommended), or SSL/TLS on port 465
Authentication
Choose between Password or OAuth2 (Azure)
Authentication Methods
Password Authentication
Requires SMTP admin credentials
Works with most standard SMTP servers
Avoid using a shared corporate relay that could be blacklisted during phishing tests
OAuth2 (Azure) – for Office 365 & Microsoft Entra ID
Azure App Registration:
In Azure Portal, register a new app.
Under Authentication, add the redirect URI:
https://<your‑lucy‑url>/smtp/oauth(no trailing slash).Record the Tenant ID, Client ID, and Client Secret.
In Settings > Common System Settings > SMTP Servers:
Select Authentication Method = OAuth2, Provider = Office 365
Enter the Azure Client ID, Client Secret, and Tenant ID
Test the connection via Lucy’s "Test Connection" tool—check console logs for success or errors.
The Lucy user account you are logged in with during authentication is the only account that will be able to send emails through this SMTP connection. To allow multiple Lucy users to send emails via this SMTP server, you must create separate SMTP entries in Lucy for each user, all connecting to the same Azure application.
Once completed, click Save to commit your SMTP server settings.
If these settings are ever updated, click Authorize to reconnect Lucy to the SMTP server.
Test Connection
To test your SMTP server settings, simply enter the sender email address (which must be the exact email address associated with your SMTP server) and a recipient email address you have access to. Then, click or select "Test" to initiate the testing process.
The response is logged just below the test input:
SMTP Error Status Codes
connect
220 domain Service ready
421 domain Service not available, closing transmission channel
HELO
250 Requested mail action okay, completed
500 Syntax error, command unrecognised
501 Syntax error in parameters or arguments
504 Command parameter not implemented
521 <domain> does not accept mail [rfc1846]
421 <domain> Service not available, closing transmission channel
EHLO
250 Requested mail action okay, completed
550 Not implemented
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
504 Command parameter not implemented
421 <domain> Service not available, closing transmission channel
250 Requested mail action okay, completed
552 Requested mail action aborted: exceeded storage allocation
451 Requested action aborted: local error in processing
452 Requested action not taken: insufficient system storage
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
421 <domain> Service not available, closing transmission channel
RCPT
250 Requested mail action okay, completed
251 User not local; will forward to <forward-path>
550 Requested action not taken: mailbox unavailable
551 User not local; please try <forward-path>
552 Requested mail action aborted: exceeded storage allocation
553 Requested action not taken: mailbox name not allowed
450 Requested mail action not taken: mailbox unavailable
451 Requested action aborted: local error in processing
452 Requested action not taken: insufficient system storage
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
503 Bad sequence of commands
521 <domain> does not accept mail [rfc1846]
421 <domain> Service not available, closing transmission channel
DATA
354 Start mail input; end with <CRLF>.<CRLF>
451 Requested action aborted: local error in processing
554 Transaction failed
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
503 Bad sequence of commands
421 <domain> Service not available, closing transmission channel
received data
250 Requested mail action okay, completed
552 Requested mail action aborted: exceeded storage allocation
554 Transaction failed
451 Requested action aborted: local error in processing
452 Requested action not taken: insufficient system storage
RSET
200 (nonstandard success response, see rfc876)
250 Requested mail action okay, completed
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
504 Command parameter not implemented
421 <domain> Service not available, closing transmission channel
SEND
250 Requested mail action okay, completed
552 Requested mail action aborted: exceeded storage allocation
451 Requested action aborted: local error in processing
452 Requested action not taken: insufficient system storage
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
502 Command not implemented
421 <domain> Service not available, closing transmission channel
SOML
250 Requested mail action okay, completed
552 Requested mail action aborted: exceeded storage allocation
451 Requested action aborted: local error in processing
452 Requested action not taken: insufficient system storage
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
502 Command not implemented
421 <domain> Service not available, closing transmission channel
SAML
250 Requested mail action okay, completed
552 Requested mail action aborted: exceeded storage allocation
451 Requested action aborted: local error in processing
452 Requested action not taken: insufficient system storage
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
502 Command not implemented
421 <domain> Service not available, closing transmission channel
VRFY
250 Requested mail action okay, completed
251 User not local; will forward to <forward-path>
550 Requested action not taken: mailbox unavailable
551 User not local; please try <forward-path>
553 Requested action not taken: mailbox name not allowed
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
502 Command not implemented
504 Command parameter not implemented
421 <domain> Service not available, closing transmission channel
EXPN
250 Requested mail action okay, completed
550 Requested action not taken: mailbox unavailable
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
502 Command not implemented
504 Command parameter not implemented
421 <domain> Service not available, closing transmission channel
HELP
211 System status, or system help reply
214 Help message
500 Syntax error, command unrecognized
501 Syntax error in parameters or arguments
502 Command not implemented
504 Command parameter not implemented
421 <domain> Service not available, closing transmission channel
NOOP
200 (nonstandard success response, see rfc876)
250 Requested mail action okay, completed
500 Syntax error, command unrecognized
421 <domain> Service not available, closing transmission channel
QUIT
221 <domain> Service closing transmission channel
500 Syntax error, command unrecognized
TURN
250 Requested mail action okay, completed
502 Command not implemented
500 Syntax error, command unrecognized
503 Bad sequence of commands
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