> ## Documentation Index
> Fetch the complete documentation index at: https://moengage-doc-2298-s2s-type-case-sensitive.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Why Does an SMTP Service Disconnect Error Occur When Testing an Email Campaign?

> Resolve the SMTP service disconnected error when testing MoEngage email campaigns, typically caused by incorrect email connector credentials.

## Problem

While testing an Email campaign, the following error message occurs:

SMTP service disconnected

<img alt="000.png" src="https://mintcdn.com/moengage-doc-2298-s2s-type-case-sensitive/Cpci9RABEv_ugaC3/images/moengage_070322.png?fit=max&auto=format&n=Cpci9RABEv_ugaC3&q=85&s=6b33e45149d510df677ba89a1bac66cc" width="988" height="536" data-path="images/moengage_070322.png" />

## Cause

Typically, this error occurs due to incorrect credentials.

## Solution

* The error originates from the SMTP connector.
* Verify whether MoEngage manages the Email connector (SendGrid) or if another provider is used.