SMTP is how SMPP Center sends emails from your platform: login alerts, OTP, password reset, credit notifications, support tickets, invoices, and bulk or marketing email. This guide covers platform SMTP (Admin), reseller SMTP (White Label), testing the connection, provider profiles for bulk email, and common fixes.

Why SMTP Matters

Mailer Type	What it does	When to use
PHP Mail (not recommended)	Uses the server’s built-in mail function	Quick tests only. Limited reliability. Attachments are not supported.
SMTP (Recommended)	Connects to your mail provider (Gmail, Google Workspace, Microsoft 365, Amazon SES, SendGrid, Mailgun, cPanel mail, etc.)	Recommended for production. Required for attachments and reliable delivery.

Always use SMTP in production.

What Gets Sent Over SMTP

Once SMTP is configured correctly, the platform can send:

Admin and user login alerts
Welcome emails and password reset links
Login / signup OTP emails
Credit add or remove notifications
Sender ID and support ticket emails
Rate / price notification emails (optional separate SMTP)
Marketing and bulk email campaigns
Postpaid invoices and expiry / low-balance reminders

Part 1: Platform SMTP (Admin Panel)

Use this for the main platform email identity and for the root/admin account mail flow.

Step 1: Open E-Mail Settings

Log in to the Admin Panel.
Go to Settings → General.
Open the E-Mail Settings tab.

You will see sections for:

Email branding (logo, footer, copyright, unsubscribe text)
E-Mail – SMTP Settings
Marketing batch mail options
Bulk E-Mail Dispatch – SMTP Provider Profile

Step 2: Set Mailer Type to SMTP

Find Mailer Type.
Select SMTP.
The SMTP fields appear.

Note shown in the panel: SMTP must be enabled if you want to send attachments in email.

Step 3: Fill SMTP Connection Fields

Field	Required	What to enter
SMTP Host	Yes	Your provider host, e.g. `smtp.gmail.com`, `smtp.office365.com`, `email-smtp.ap-south-1.amazonaws.com`, or `mail.yourdomain.com`
SMTP Encryption	Yes	SSL or STARTTLS
SMTP Port	Yes	Usually 465 for SSL, 587 for STARTTLS (the UI often auto-fills this when you change encryption)
From Name	Yes	Display name recipients see, e.g. `SMPP Center Alerts`
SMTP Username	Optional*	Leave blank for Gmail / most providers (From E-Mail is used). For AWS SES, enter the SMTP username starting with `AKIA...`
From E-Mail	Yes	A verified sender address, e.g. `noreply@yourdomain.com`. Never put an AWS `AKIA...` username here
Reply-To E-Mail	Optional	Where replies should go. Leave blank to use the From address
SMTP Auth Mode	Optional	Leave Default (automatic) unless your provider requires LOGIN, PLAIN, or CRAM-MD5
SMTP Password	Yes	Mailbox password or app password / SMTP secret

*AWS SES and some enterprise relays require Username.

Step 4: Set Admin Notification Address

On the General settings area (same Settings page), confirm:

Admin Notification E-Mail – where test mail and admin alerts are delivered (comma-separated for multiple)
Site E-Mail (MAIL FROM) – platform identity used in some notification flows

The Test Connection feature sends the test message to your Admin Notification E-Mail.

Step 5: Test Connection

Click Test Connection.
Wait for the result.
Success shows: SMTP Connected
Check the Admin Notification inbox (and spam folder) for a Test Mail message.

If the test fails, fix credentials or network access first. Do not assume Save alone means mail will work.

Step 6: Save Settings

Click Save on General settings so host, encryption, port, From details, and password are stored. The password is stored encrypted.

Part 2: Reseller SMTP (White Label)

Resellers who send their own branded emails need their own SMTP under White Label. Without this, reseller bulk email and many reseller-branded notifications will not send correctly.

Path A: Reseller configures their own SMTP

Log in to the Reseller / User Panel.
Open White Label.
Go to the Email category.
Open SMTP Connectivity.
Fill the same style of fields as Admin SMTP (Host, Encryption, Port, From Name, Username, From E-Mail, Password, optional Reply-To and Auth Mode).
Optionally set an SMTP Provider Profile for bulk dispatch (see Part 4).
Click Test Connection.
On success (SMTP Connected), Save.

If SMTP Connectivity is missing, sending email from the reseller panel typically shows a message asking you to configure and save SMTP under White Label first.

Path B: Admin configures SMTP for a reseller

Admin Panel → Users → edit the reseller.
Open the Reseller tab.
Find Reseller SMTP Settings.
Enter host and related fields.
Leave Password blank on update if you want to keep the existing password.
Use Test Connection, then save the user.

These values are stored the same way as White Label SMTP Connectivity.

Optional: Rate Notification SMTP

Under White Label you may also see Rate Notification SMTP. Use a separate mailbox if price/rate emails should go out from a different From address than general alerts. If it is not set, the default SMTP Connectivity is used.

Part 3: Encryption and Port Cheat Sheet

Encryption	Typical port	Common providers
SSL	465	Many cPanel / hosting SMTP setups
STARTTLS	587	Gmail, Google Workspace, Microsoft 365, many transactional providers

Tips:

Prefer 587 + STARTTLS or 465 + SSL as your provider documents.
Port 25 is often blocked by cloud hosts. Avoid it unless your provider explicitly requires it and the server allows outbound 25.
Firewall / security groups must allow outbound TCP to your SMTP host on the chosen port.

Part 4: SMTP Provider Profile (Bulk / Marketing Email)

This is not a second SMTP account. It controls how fast bulk email is dispatched so you stay within provider limits and avoid temporary blocks.

Where to set it

Admin: Settings → General → E-Mail Settings → Bulk E-Mail Dispatch – SMTP Provider Profile
Reseller: White Label → SMTP Connectivity → Bulk E-Mail Dispatch Settings – SMTP Provider Profile

Profile options

Profile	Rough pacing	Best for
Google Workspace (Safe)	About 20 emails/min	Gmail / Google Workspace
Standard	About 120 emails/min	Most shared / business SMTP
High Volume	About 600 emails/min	SendGrid, Mailgun, Amazon SES, similar
Enterprise	About 1200 emails/min	Dedicated high-capacity relays
Custom	You set batch size, rate, and reconnect interval	Advanced tuning
Use platform default (reseller)	Falls back to admin settings, then safe defaults	When unsure

If you leave profile unset, the platform can auto-detect from the SMTP host (for example Google/Outlook-style hosts use a safer profile; SendGrid/Mailgun/SES-style hosts use higher volume).

Marketing batch settings (Admin)

Also configure:

Enable Batch E-Mail
Batch E-Mail Count

Then send campaigns from Marketing → Send E-mail (Admin) or Send E-Mail (Reseller panel, after SMTP Connectivity is saved).

Part 5: Provider-Specific Setup Notes

Gmail / Google Workspace

Use host smtp.gmail.com.
Encryption: STARTTLS, port 587 (or SSL 465 if your account supports it).
Enable 2-Step Verification and create an App Password. Use that as SMTP Password.
Leave SMTP Username blank (From E-Mail is used).
From E-Mail must be the Gmail / Workspace address (or an allowed send-as alias).
Prefer the Google Workspace provider profile for bulk sends.

Microsoft 365 / Outlook

Host is usually smtp.office365.com.
STARTTLS + port 587.
Username is often the full mailbox address.
From address must be allowed for that mailbox.
Use a conservative provider profile if sending in volume.

Amazon SES

Host looks like email-smtp.<region>.amazonaws.com.
SMTP Username = SES SMTP credentials user (AKIA...).
From E-Mail = a verified SES identity (domain or email). Never put AKIA... in From E-Mail.
Use the SES SMTP password from the console.
Prefer High Volume profile for bulk.
Confirm SES sandbox / production access and region match your host.

SendGrid / Mailgun / similar

Use the SMTP host from the provider dashboard.
Username/password (or API key as password) as documented by the provider.
From address must be authenticated (SPF/DKIM domain).
Prefer High Volume profile.

cPanel / custom domain mail

Host is often mail.yourdomain.com or the hostname your host provides.
Use the full email as From (and usually as username if required).
Match SSL/465 or STARTTLS/587 to your host’s mail docs.
Start with Standard profile.

Part 6: End-to-End Verification Checklist

After saving SMTP:

Test Connection succeeds with SMTP Connected.
Test email arrives in Admin Notification / reseller session inbox.
Trigger a real event (password reset request, login alert, or a small Send E-mail campaign).
Confirm From Name and From E-Mail look correct to the recipient.
If using Reply-To, reply to the message and confirm it lands in the right mailbox.
For bulk mail, confirm the Provider Profile matches your provider’s sending limits.

Part 7: Troubleshooting

Symptom	Likely cause	What to do
Test fails / SMTP Not Connected	Wrong host, port, encryption, user, or password	Re-check provider docs; try STARTTLS/587 vs SSL/465; regenerate app password
Authentication failed / `535`	Bad password or auth method	App password for Google; correct SES SMTP user; try Auth Mode LOGIN or PLAIN
Connection timed out / refused	Firewall, blocked port, wrong host	Allow outbound 465/587; confirm host and region
From E-Mail validation error about AWS username	`AKIA...` placed in From E-Mail	Move `AKIA...` to SMTP Username; put verified email in From
Please fill in all SMTP fields	Incomplete form	Fill required host, encryption, port, From, password
Please configure SMTP Connectivity under White Label	Reseller SMTP missing	Reseller → White Label → SMTP Connectivity → Test → Save
Emails paused / SMTP temporarily disabled after repeated failures	Auth guard after repeated handshake failures	Fix credentials, Test Connection successfully, or ask Admin to reset the reseller SMTP auth guard on the user Reseller tab
Attachments missing / not sent	Mailer Type is PHP Mail	Switch Mailer Type to SMTP
Bulk mail slow or provider blocks	Wrong Provider Profile	Use Google Workspace for Gmail; High Volume for SES/SendGrid/Mailgun; or Custom with lower rate
Works for Admin but not Reseller	Only platform SMTP set	Configure reseller White Label SMTP (or Admin → User → Reseller SMTP)

Password tips

Prefer app passwords / SMTP secrets over the main mailbox password when the provider offers them.
After a successful save, leave password blank on later edits if you are not changing it (admin reseller form supports this).
Avoid copying passwords with hidden spaces or HTML-encoded characters.

Deliverability tips (beyond SMTP login)

SMTP “connected” only means the server accepted the message. For inbox placement:

Send from your own domain.
Set SPF, DKIM, and preferably DMARC for that domain.
Use a recognizable From Name.
Keep marketing content compliant and include a clear unsubscribe footer (platform email footer settings support this).

Quick Setup Summary

Admin (platform):
Settings → General → E-Mail Settings → Mailer Type = SMTP → fill host/encryption/port/From/password → Test Connection → Save → set Provider Profile for bulk if needed.

Reseller:
White Label → SMTP Connectivity → fill and Test → Save → optional Rate Notification SMTP → optional Provider Profile.

Admin for a reseller:
Users → Edit → Reseller tab → Reseller SMTP Settings → Test → Save.

Need More Help?

If Test Connection still fails after verifying host, port, encryption, and credentials, contact your SMTP provider’s support with the exact error text from the Test Connection result, and share that message with SMPP Center support if you need platform-side assistance.

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How to Set Up SMTP in SMPP Center