Every so often the messages I compose to send sit in the Outbox folder even after having been sent.

I haven't been able to understand what causes or triggers this behaviour but have seen it happen quite a lot of times. I only write plain text emails and it has happened when there's only one recipient, multiple, attachments added to email, etc...

Has anyone ever came across with this bug?

It's very, very, very annoying. Specially when you don't notice it and it sends the same email over and over again.

What's causing this and how can it be fixed?


Thank you,
Adriano