Email sent by Thunderbird feeding into ERPNext


I am using ERPNext V13, I am receiving emails sent by clients to an IMAP email inbox from where they are pulled into the ERPNext inbox and automatically attached to the relevant client record. I would like to use Thunderbird for all email conversations but if I send out emails to those clients using Thunderbird including BCC to the IMAP email inbox they pop up nicely within the IMAP inbox but are not pulled into the ERPNext inbox. Why is this? Is there a way I can copy/forward/rewrite outgoing emails sent by thunderbird so that they are automatically pulled into the ERPNext inbox?

Kind regards,