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Signature 365 SMTP host list and IP whitelist

    Microsoft 365 integration

    When Microsoft 365 server-side signatures are configured, email is routed from Microsoft 365 to Signature 365 for signature injection, and back again to Microsoft 365 for delivery. Email is routed via Signature 365 using the Simple Mail Transfer Protocol (SMTP). You can find the host for the region where your Signature 365 account is hosted in the table below:

    Region Region code Host
    Australia au smtp.au.signature365.net
    Canada ca smtp.ca.signature365.net
    European Union eu smtp.eu.signature365.net
    United Arab Emirates ae smtp.ae.signature365.net
    United Kingdom uk smtp.uk.signature365.net
    United States us smtp.us.signature365.net

    If you add additional include statements to the Sender Policy Framework (SPF) record for your domain and your SPF record exceeds the 10 Domain Name System (DNS) lookup limit, you can instead add the IP addresses directly. You can find the IP addresses for the region where your Signature 365 account is hosted in the table below:

    Region Region code SPF record IP addresses
    Australia au spf.au.signature365.net 20.53.65.59
    Canada ca spf.ca.signature365.net 20.48.141.200
    European Union eu spf.eu.signature365.net 20.54.238.131
    United Arab Emirates ae spf.ae.signature365.net 20.74.238.135
    United Kingdom uk spf.uk.signature365.net 20.49.163.140
    United States us spf.us.signature365.net 52.148.165.43