How to prevent mail from Wordpress website from being flagged as spam on Exchange online server -

i have website; let's call abc.com. it's e-mail handled office365. migrated sharepoint environment different webhost (godaddy). have tried using wp mail smtp plugin option send e-mails, fails send.

my settings are:

smtp: smtp.office365.com port: 587 encryption: use tls authentication: use smtp 

sending fails error:

smtp error: failed connect server: connection refused (111) 

using default wp mail settings below works send e-mail addresses outside domain, messages flagged spam on addresses within domain.

header = 'from: '.get_option('blogname').' <wordpress@abc.com>' 

i have e-mail routing set remote mail exchanger. i've tried adding address wordpress@abc.com exchange's allowed list/whitelist, , tried adding host ip trusted ips on server - still doesn't work.

as far i'm aware, godaddy not let send mail external smtp providers. if you're not able choose host (which i'd recommend if can!), you'll need use wp mail , send mail local address @ same domain, hosted godaddy.

if wanted to, set alias send elsewhere.

there's more background on over @ wordpress.org, such this thread , this thread.

edit

just realised postman smtp plugin claims can around godaddy's filtering using https:

"even hosts block standard smtp ports, godaddy or bluehost, can't stop email postman can deliver via https if can't use smtp."

so maybe give plugin go instead. :)