[MlMt] Attachment download notifications

[Eric Sharakan]

Hi, I just noticed that when I click the download button next to an attachment, I get a notification in macOS's Notification Center.  In System Preferences->Notifications I have MM set to "Allow Notifications", have the Mail alert style set to "None", and leave the "Show in Notification Center" checkbox unchecked, yet I still receive these notifications.

MailMate r5870, macOS 12.2

Thanks.

-Eric