Attachments appear corrupted

[SKaero]

I'm not disagreeing with you that its not mailserver or the attachments but it could be something in one of them that is causing RoundCube to break. I'm just trying to rule out the other major parts of the platform since it doesn't seem to be related to nginx or php5-fpm.

[JohnDoh]

have you checked that none of the rc files have a BOM at the top? I mean things like the config files or any localisation ones if you have edited any? AFAIK no files in rc should have a BOM and if you look at older posts in the forum you'll see that this issue has occured when they have been added by accident.