Welcome Laurainfl,
Thank you for using Apple Support Communities. Based on your post, you have issues sending emails on your iPhone. We'll do our best to assist with this.
For issues sending emails on your iPhone, we'd start here: If you can’t send email on your iPhone, iPad, or iPod touch
In case you need that outgoing mail server information for your email account, you can type in your email here to see if Apple has those settings: Mail Support
Otherwise, you may need to contact Hotmail support for those specific settings: Microsoft Support
Let us know if this helps out, take care.