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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
aesmtp.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
aespf.ae.signature365.net20.74.238.135
United Kingdom
uk
spf.uk.signature365.net
20.49.163.140
United States
us
spf.us.signature365.net
52.148.165.43

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