In order to send emails via Elastic Email servers while using Mautic software - you will need to properly configure your Mautic.
Navigate to Email Settings under Configuration panel inside Mautic Automation Software.
To send your emails, use following settings :
Service to Send Mail Through: Other SMTP Server
SMTP Host: smtp.elasticemail.com
SMTP Port: 2525
SMTP Encryption Type: None / SSL / TLS
SMTP Authentication Mode: CRAM-MD5 (Alternative: Login)
Username for selected email service: The username of your chosen SMTP Credential
Password for the selected email service: The password of the same SMTP Credential
Alternative Settings - please use these settings if your port 2525 is closed and you cannot connect via it :
SMTP Port: 25 or 465 or 587
Alternatively, you can choose Elastic Email preset settings which will automatically set the required configuration:
Webhooks for Mautic (Marketing PRO and Email API PRO)
If you are having any problems with setting up HTTP Webhook Notifications for your Mautic integration, please follow these instructions:
1) Login to your Elastic Email account and go to Settings -> Notification.
2) Fill in the Notification URL as http://your-mautic-url.tld/mailer/elasticemail/callback
3) Check status boxes that are relevant for you
Source: https://www.mautic.org/docs/en/emails/bounce_management.html
(Elastic Email Webhook section)