Double check your SMTP Server settings on your Mac. SMTP handles outgoing mail. Incoming is obviously correct and the correct settings are on your phone. I suspect a typo in either the address or password as you typed it in. If they appear correct and it still won't work, remove the account and start again, on the Mac.
What is Markdown?
Markdown lets you add more formatting to your post. Simply type in your post and it will display as written.
If you wish to add bold or italic characters, add a hyperlink to another website, a heading or a horizontal line, simply use the relevent icons above the text input field.
A preview of your post will appear in the grey box below. If you make a change and you're not happy, simply press the back arrow icon to undo.