An email sent with an attachment shows up in the sent folder of both programs, but in outlook sometimes the sent email doesn't look like it was sent. It shows the send box and has the message that this email hasn't been sent. But it has been sent. I've confirmed that it has. If you click on the send button, the email is sent a second time. It's always emails with attachments. Emails without attachments are no problem.
Has anyone seen this before? How do I fix this?