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"Invalid certificate" message in MacMail Mojave

I'm getting the "The certificate for this server is invalid" message when I try to go online with one of my IMAP mail accounts in MacMail. An earlier similar conversation had said to go to the Security and Privacy section of System Preferences and where it says "Allow apps downloaded from," to select "Anywhere." In Mohave, selecting "Anywhere" doesn't appear to be an option.


Is there another workaround I can try?

iMac 27″, macOS 10.14

Posted on Jun 1, 2020 8:49 AM

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Question marked as Top-ranking reply

Posted on Jun 1, 2020 9:06 AM

Allowing Apps from anywhere was removed from Mojave and later. That has nothing to do with your problem. Two entirely different certificates for different usage.


Maybe the certificate is actually invalid. You would need a valid certificate to establish encrypted communication with the email server.


Only two things I can think of to try:


Toggle TLS/SSL

  1. Open Mail Preferences and select the Accounts tab.
  2. Select the email account
  3. Click on the Server Settings tab.
  4. Uncheck Automatically manage connection settings.
  5. Toggle the Use TLS/SSL check box


Remove the account and then re-add it

1 reply
Question marked as Top-ranking reply

Jun 1, 2020 9:06 AM in response to by3407

Allowing Apps from anywhere was removed from Mojave and later. That has nothing to do with your problem. Two entirely different certificates for different usage.


Maybe the certificate is actually invalid. You would need a valid certificate to establish encrypted communication with the email server.


Only two things I can think of to try:


Toggle TLS/SSL

  1. Open Mail Preferences and select the Accounts tab.
  2. Select the email account
  3. Click on the Server Settings tab.
  4. Uncheck Automatically manage connection settings.
  5. Toggle the Use TLS/SSL check box


Remove the account and then re-add it

"Invalid certificate" message in MacMail Mojave

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