Partial solution for Yosemite mail smtp not syncing with blueyonder-gmail with attachments

I have a 2013 iMac with Yosemite recently installed, I use the Mail app for my blueyonder.co.uk email address that is run by virgin media using gmail servers.

Since upgrading to Yosemite I have noticed when sending emails with attachments over around 200KB that the email appeared to not be sent, i.e. it didn't appear in the Sent folder.

However, I checked with a test address and these emails were successfully sending, they just weren't being copied to the gmail server's Sent folder, and therefore not synced to the Mail app's Sent folder. I think this is a Yosemite Mail app bug that will hopefully be fixed soon, everything was working correctly under Mavericks.

After trying lots of possible solutions I have, for now at least, found a temporary work around.

Initially just to aid testing I set up my emails to automatically Bcc myself in Mail->Preferences->Composing->Composing: check the Automatically checkbox and select Bcc: , close the window and select Save if asked.

This works as expected and send me a copy of the email I've just sent even with attachments of any size and over the limit of around 200KB I'd noticed above.

BUT what it also seems to do is force the gmail server syncing to work correctly somehow, so now I get the Bcc email in my inbox AND I get the Sent folder updated correctly. At this point this gives me another email to delete but at least I know the emails have been sent and my Sent folder is updated correctly for searching etc.

Fingers crossed this is fixed soon.