Sent Emails are displayed twice in the Sent folder

[glenn2223 (Glenn)]

Looks like a duplicate of

Duplication of Sent Mail

Some mail services, like Outlook, already automatically copy sent mail to the Sent folder. When Mailspring sends a message, it does the exact same thing, resulting in multiple copies of the message. This replication gets worse with multiple recipients, including in BCC fields. This half of the problem is related to read receipts. (See BCC'ing many recipients splits the message into one for each recipient · Issue #1669 · Foundry376/Mailspring · GitHub) However, the message still is only being s…