# Unable to connect to O365 Mail Server

**URL:** <https://help.nextcloud.com/t/unable-to-connect-to-o365-mail-server/79586>\
**Category:** ℹ️ Support\
**Created:** [April 28, 2020, 1:55pm UTC](https://help.nextcloud.com/t/unable-to-connect-to-o365-mail-server/79586 "2020-04-28T13:55:43Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![tflidd](https://help.nextcloud.com/letter_avatar/tflidd/32/6_22734026db12803ebb3e059622ac3534.png) [@tflidd](https://help.nextcloud.com/u/tflidd)\
**Post date:** [April 30, 2020, 8:25am UTC](https://help.nextcloud.com/t/unable-to-connect-to-o365-mail-server/79586/2 "2020-04-30T08:25:22Z")

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It’s a problem with the certificate of the mail server. Did you try the option STARTTLS for encryption ([Basic mail settings for 0365](https://help.nextcloud.com/t/basic-mail-settings-for-0365/57746/4))

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_[View the full topic](https://help.nextcloud.com/t/unable-to-connect-to-o365-mail-server/79586)._