[MlMt] S/MIME signing in MM

David Green dgreenbhm at gmail.com
Fri Aug 24 18:02:26 EDT 2018

On 24 Aug 2018, at 6:41, Alexandre Takacs wrote:

> Any idea ?

In case it is helpful to anyone, here are my notes (alas, made after not 
as I did it so far warning):

Using FireFox, go to Comodo - 

Fill out form being sure to log the revocation password (in 1Password in 
my case in Secure Note titled “Comodo Certs”).

Act on the e-mail that comes out of the process ensuring that FireFox is 
used for this step as well.  This will put the Certificate and Private 
Key into FireFox which can be “seen” at Preferences | Privacy & 
Security “ | Certificates | and select “View Certificates…”.

Select the certificate, choose Backup…

Note directory where the information will be placed.  Ensure the format 
is “PKCS12 Files”.  Pick a name perhaps with the e-mail address in 
it and save the file.  You will be asked for a backup password.  Save 
this into the 1Password note as well.  This password will be needed to 
unlock the private key.

Open Keychain Access, provide appropriate password to unlock if needed.

Select Login and Certificates.

Click on “+” and select the .p12 file made above.   Select 
“Save” and supply the backup password chosen earlier.

Add “MailMate” to the list of applications that can access this.  
Later when this happens, you may have to answer again with the Keychain 
Access (not backup) password.  It may be that this is more involved if 
one did not pre-populate access by the application and the backup 
password would be needed.

In MailMate, ensure that S/MIME is on under Composer in the Security 
Pane of MailMate preferences.

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