Hi Zang,
I have attached my entire maillog file for review. where a user krupali.patel@myiredmaildomain tries to send Emails with attachments to other google domain users or on to hotmail.co.uk or others, emails are going fine not showing any issues in logs but at other end emails are not received.
When there is a single DOC file it is not getting delivered, when she zip the same DOC file and sends back still it is not received at other end. We are also not getting any delivery failure notice or anything from other domains. We checked DKIM signing and SPF records which are also fine, no blocking on Spamhause database but still don't know why emails are not getting delivered at other end.
Request you to look into it and guide further if found anything as I think due to this issue we will have to close down our server and move on to other suppliers which I do not want to do.