FAQ: mailRelay service setup

Applies to:

• mailRelay

Description:

Integration with the mailRelay service is relatively simple as it is provided as a standards compliant SMTP mail service. However, when first adopting the service there are a few considerations for successful onboard:

• Service Access Control
• Domain Configuration
• SPF Configuration
• Firewall considerations
• SMTP Relay Configuration

Each of the topics are briefly discussed to provide the necessary guidance for successful setup. In the event of any further queries please open a support ticket via the Client Portal or email our support team.

Service Access Control

Access to the mailRelay service is controlled through a combination of the sending IP address and domain name pair.

For example, if you activate 193.203.117.25 with domain example.co.uk we will only permit emails to be sent from @example.co.uk when originating from IP address 193.203.117.25. Any attempts to send email from 193.203.117.25 from any other domains will be rejected, similarly we will only permit mail to be sent from @example.co.uk when originating from the 193.203.117.25. Where multiple IP addresses and/or domains are authorised for a single mailRelay service 'any, any' operation applies such that any of the authorised IP addresses can send from any of the authorised domain.  If you require separation you must purchase seperate mailRelay services.

Should you wish to change the IP address and/or domains associated with the mailRelay service please open a support ticket via the Client Portal or email our support team.

Domain Configuration

Access to the mailRelay service is provided 'domain locked' meaning we will only permit sending from the authorised domain(s) associated with the service. Verification is completed by confirming the presence of the SPF record (see 'SPF Configuration') within your domain/zone. In some instances we may also request that you setup a custom TXT record as an additional verification step, in which case our support team will advise the required record.

SPF, DKIM & DMARC Configuration

Please refer to our Knowledgebase article which discusses SPF, DKIM and DMARC in general and the required configuration.

Firewall Configuration

If you are sending from an environment which restricts access to the Internet it is necessary to ensure that you open access through your firewalls to ensure that you can connect. The service is provided via two separate data centres with access load balanced across and within the locations. It is therefore important that all load balancer IP addresses are accessible through your firewall as any or all may be active at any given time. 

Note: Whilst it is mandatory to open access to all IP addresses it is only necessary to open access to one port, though opening all three may provide some application flexibility. It is important if you do not open all ports that you open the same port across all IP addresses to prevent any issues if we switch the service between IP addresses.

SMTP Relay Configuration

In order to make use of the SMTP relay service you will need to send outbound mail via the following smarthosts:

   relay1.uksmtp.co.uk
   relay2.uksmtp.co.uk

For redundancy you should configure your mail server to relay via both systems.  If your software only allows a single smarthost to be configured please specify the following:

   relay.uksmtp.co.uk

The service is available via the following ports:

• TCP/25
• TCP/587
• TCP/2525

The service supports TLS using the STARTTLS SMTP verb. Verify your mail server or application is configured to use STARTTLS to benefit from secured communications to the mailRelay service.

If you are configuring a Microsoft Exchange send connector this article provides a suggested configuration

Other Questions

This quick start guide is designed to answer the most common setup questions but should have any further questions please open a support ticket via the Client Portal or email our support team.