Relay Page

Use this page to allow traffic through the relay, turn on antimalware and configure how to relay mail.

Navigation: EMAIL > SMTP > Relay.

SMTP relay
Enable mail relay Turns on relaying after configuring incoming and outgoing relaying.
Maximum email size (MB) The maximum email size, in megabytes, that is accepted. Any email larger than this limit are rejected.
Maximum bounce size (KB) The maximum size of an email, in kilobytes, used in a bounce email.
Time to hold undeliverable mail The amount of time an email is held in the queue if it can't be sent. An attempt to send all email that's held in the queue is made periodically.
Enable transparent SMTP relay Captures outgoing email and relays it.
Enable anti-malware scanning Turns on antimalware scanning for relayed email.
Action to perform on malware
  • Determines what to do if malware is found in relayed email:
  • Action Description
    Drop (discard) email Discard the email, without notifying the sender or intended recipient.
    Bounce email (warn sender) Return the email to the sender, along with a warning message.
    Neutralize email Send a warning email to the recipient, with the original email as an attachment.
    Allow email delivery Allow the email to be delivered, and the malware is logged.
    Transparent SMTP interfaces
    Port 1.57 Solutions The interface(s) SMTP traffic will be transparently captured from
    Port 3 S2 Imaging Network
    Port 4 S4/S8 Imaging Network
    Port 5 S10/S14 Imaging Network
    IP exception list Any IP addresses, subnets or ranges that should not be transparently proxied.
    Advanced » Expands the view to show the following sections and options.
    SMTP name
    Use system hostname Uses the SMTP hostname when relaying email.
    User defined hostname Your defined host name to use when relaying email.
    External mail relay
    Enable relay host Turns on the relay host to send outgoing email to another relay within an existing email infrastructure.
    Relay host The IP address or hostname of the relay.
    Username (if applicable) The username, if needed by the remote relay.
    Password The password, if needed by the remote relay.
    Non-standard SMTP checking
    Use strict HELO checks Ensures that the initial communication between a connecting SMTP client and the email relay is valid.
    Sender domain validity Checks that the sender domain is formatted correctly and has a real IP address.
    Recipient domain validity Checks that all recipient domains are formatted correctly and have real IP addresses.
    External sender domain spoofing Checks if the sender of incoming email is falsely using an internally relayed domain in their From address. Emails are rejected if the sender’s email address purports to be from a domain listed on the incoming page, but the sender’s IP address cannot be found on the outgoing page.