macOS Sonoma removes support for classic Mail plugins

[barijaona]

Is your feature request related to a problem? Please describe.
Classic Mail plugins are deprecated in macOS Sonoma.

Describe the solution you would like
Plugins have to be based on MailKit

[jaedon]

Hi @barijaona
Thank you for supporting Mail. Do you have any ideas or plans for moving MailKit?

[barijaona]

Hi,
I intend to, but I have yet to asses the size of the project.

Pointers to examples welcome.

[jaedon]

I'm worried. MailKit is very restricted. It seems that MEContentBlocker, MEMessageActionHandler, MEComposeSessionHandler, and MEMessageSecurityHandler are not usable for us.

[barijaona]

I don't know if macOS Sonoma's Mail application solves the main reason I use UniversalMailer : the dispersal of messages passing through Microsoft Exchange servers into ATT00001.htm or ATT0001.txt attachments.

If this is not solved, adapting UniversalMailer will remain important.

MEComposeSessionHandler seems relatively restrictive: many properties of mail message are marked read only.

But I remain hopeful we can hack MEMessageSecurityHandler : the idea is to use the protocol to modify the message instead of encrypting it.

[VitaliyYakob]

@barijaona
Hi!
Do you have any ideas for updating the plugin? Maybe a beta version?

I don't want to believe that MailKit killed this plugin.

[jorgehezd]

I don't know if macOS Sonoma's Mail application solves the main reason I use UniversalMailer : the dispersal of messages passing through Microsoft Exchange servers into ATT00001.htm or ATT0001.txt attachments.

If this is not solved, adapting UniversalMailer will remain important.

MEComposeSessionHandler seems relatively restrictive: many properties of mail message are marked read only.

But I remain hopeful we can hack MEMessageSecurityHandler : the idea is to use the protocol to modify the message instead of encrypting it.

I confirm that Sonoma doesn't solve the issue. But I noticed that the problem is present only on the Outlook App on Windows OS.