Available Outgoing Ports
The default and recommended outgoing port is 587 (this supports STARTTLS which will be automatically employed if the connecting server supports it). Port 465 and port 25 can also be utilized for outbound connections, but the likelihood of needing to use these is rare and not recommended.
All outgoing connections require TLS before SMTP AUTH.
Filtering Server Hostnames
These are the hostnames to configure in your Sending MTA/Server. Please refer to your manufacturers documentation on how to configure for your environment:
- SMTP outbound filter hostname:
smtp.antispamcloud.com(port 587/465/25)
We do not recommend using port 25 for sending outbound mail to the filter.
Regional specific records
These regional specific records are only to be used if you require mail to be received by servers in a specific region.
We do not recommend using these regional records unless absolutely necessary.
Using the below records forces usage of our EU/US/UK/AU/CA/ZA server infrastructure, however deliveries may still be routed via our international platform. Please contact our support team by raising a support ticket through N-AbleMe to force-set your customer ID to EU/US-only delivery servers to ensure messages are not re-routed internationally.
- EU-only:
eu.smtp.antispamcloud.com(port 587/465/25) - US-only:
us.smtp.antispamcloud.com(port 587/465/25) - UK-only:
uk.smtp.antispamcloud.com(port 587/465/25) - AU-only:
au.smtp.antispamcloud.com(port 587/465/25) - CA-only:
ca.smtp.antispamcloud.com(port 587/465/25) - ZA-only:
za.smtp.antispamcloud.com(port 587/465/25)
We do not recommend using port 25 for sending outbound mail to the filter.
Local Cloud Only
If you wish to use port 25 for outgoing email, you will need to specify a secondary IP which will be configured to listen to port 25. You will then be required to update the sending servers.
Please note, using port 25 is not recommended for outgoing mail. You should also restrict outgoing mail in your firewall to stop scammers or malware from sending mail from your IP addresses.
To configure this, please contact our support team by raising a support ticket through N-AbleMe.
Connection Limits
The filtering servers by default will accept a maximum of 10 concurrent connections from your servers. This ensures optimal delivery speeds.
To prevent your server from getting temporary rejects "421 Too many concurrent SMTP connections from this IP address; please try again later" and queuing the messages, please ensure you configure your MTA to open a maximum of 10 connections concurrently. This will prevent a backlog building up on your server(s).
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