Exchange Online
A Microsoft email and calendaring hosted service.
6,190 questions
Whitelist IP as safe sender
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SY_MSO
166
Reputation points
We have one appliance hosted on an external IP address. The appliance has SMTP configuration. When we give SMTP configs for O365, delivery to external recipients fails but internal recipients are able to receive the message successfully.
Tried adding IP to allow list in Connection filter in Defender portal but still unable to send emails to external users.
Error: Failed to send an email from the user with id '11' to the user with id '-99' due to the following error: "SMTP Error: The following recipients failed: : TenantAttribution; Relay Access Denied [TO1CAN01FT012.eop-CAN01.prod.protection.outlook.com] "
Exchange Online
{count} votes
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Alisson Soares Araujo 0 Reputation points2023-05-17T00:13:28.5933333+00:00 HI @SY_MSO Does your Appliance has it's own SMTP service or are you connecting to Exchange Online SMTP service (Exchange user account/password) to send e-mails? I mean.. Is your appliance an SMTP client of Exchange Online?
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