Which mail provider do you use and which SMTP extension do you use

[Kovalski]

I have an office 365 account and can't get it to send emails. But my regular shared hosting mail sends it just fine.

I use Magepal SMTP. I tried others on their demo stores but it does same thing, throw an error:

5.7.3 Authentication unsuccessful [GVAP278CA0009.CHEP278.PROD.OUTLOOK.COM]

[Manish Mittal]

@Kovalski 

You can use Mageplaza, this is very good plugin:

https://www.mageplaza.com/magento-2-smtp/

Or Mandrill

https://github.com/ebizmarts/magento2-mandrill

[gaurav_harsh1]

@Kovalski 

If you are able to send email from any other mail system (gmail, Yahoo Mail, Mail.com etc), then this issue is not related to any Magento extension, it's a mail server side issue.

Here are some suggestions :

• Please check if the TLS/SSL is required when you configured Outgoing server. If it is not enabled, please enable it.
• For this authentication error, please change your account credential and then check the issue.

There are solutions given on Microsoft community, please check once here :

https://answers.microsoft.com/en-us/msoffice/forum/all/smtpoffice365com-535-573-authentication/2e708...