Cannot Send Email to Exchange Online - Remote Certificate is Invalid
We have recently migrated from Exchange on premise to Exchange online with Microsoft 365. When updating the SMTP information for Deploy, I am getting the following error:
"The remote certificate is invalid according to the validation procedure."
SMTP Server: smtp.office365.com:587
SSL/TLS: enabled (need only TLS)
Using account email address & password, tried multiple accounts
Anyone successfully got this setup, any suggestions would be greatly appreciated. I have a ticket open with PDQ and Microsoft but have not found a solution yet.
have you enabled the SMTP AUTH in the office365 admin?
for more info check https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/authenticated-client-smtp-submission
Thanks, forgot this was here! Yes, that is setup. I did eventually find the problem. We were running an email encryption service through our firewall prior to the migration. The firewall rule was interfering with some local application's ability to send mail. Once that was disabled, this (and a couple more) were working again.
Cool, nice to see you were able to fix it.
Have a great day!
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