2009 imac, os x 10.6.8. Outlook will not let me attach any documents to email. Any help please?

Hi, I have an Imac 2009, running osx 10.6.8. Yes, I know it's old. Outlook will not let me attach any size documents to my emails. It keeps telling me I have exceeded the attachment limit size, even when it was 850kb. I can send written emails and receive emails with large attachments.

Everything was working great with hotmail and I'm pretty sure things were working ok with outlook for a start.

I log onto my outlook account through safari browser. I do not use my mail app to send or receive any emails. It's not setup. I do not have outlook downloaded on my imac.

I have just bought a new windows laptop, which can send large attachment through outlook fine, but I like my old imac and love it as my desktop and wish to keep using it.

Can someone please help me get a bit longer out of my old desktop??