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Cannot Send Email to Exchange Online - Remote Certificate is Invalid

Bethany Anderson

January 14, 2021 17:49

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.

Thanks,
Bethany

Comments

3 comments

Marcel Lipovsky
February 13, 2021 23:26

Hi Bethany,
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

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Bethany Anderson
February 16, 2021 14:08

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.

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Marcel Lipovsky
February 16, 2021 21:25

Cool, nice to see you were able to fix it.

Have a great day!

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