Won't send any kind of PDF files

My setup is don as following:
Operating system: OSX 10.11.3
Sofware versin: 16.2.9
email adress: my outlook email
Use custom SMTP server: Yes
Host: smtp-mail.outlook.com
Port: 587
Use SSL: Yes
SMTP Authentication: Yes
User name: my outlook email
Password: my outlook password

Every time i try to send PDF’s via mail it tells me "Message could not be sent."
Is there any way to fix this?

And when you turn off custom SMTP option, will it send?

That was just that simpel of a trick and it worked perfectly.

I have been trying to get it to work for days now…

Thanks for the help.

You should still try to get custom SMTP option working. Have you tried to use the same SMTP settings in some other email client such as Thunderbird or similar?

I have testet and used the setup on the same machine in microsoft office outlook 2016 and there it’s working…