CiviCRM does not send mail to microsoft based webmail clients (outlook, hotmail and live)

CiviCRM Version 4.7.4 on Wordpress

ECDHE-RSA-AES256-SHA384:256 CV=yes: SMTP error from remote mail server after MAIL FROM: email address redacted SIZE=1620: 550 SC-001 (BAY004-MC1F36)

This has been happening consistently over time, is there any way to track or identify where the process is falling down?

We have tested thirdsectordumgal (via Civi) to live, which failed. live (via civi) to thirdsectordumgal appeared to work, but has not shown up. live (via civi) to live also failed.

We use Sendmail to send out the mail as SMTP authorisation has not worked in the past.

2 Answers 2


Microsoft's mail services have blocked your mail server.

Their specific reasons for blocking may vary (and their server's response codes will guide you here to some degree), but there are a variety of things you can do to improve the situation.

Alternatively you might consider one of the hosted mail provider plugins available for CiviCRM - managing relations with mail providers can be a big task, and outsourcing that may save you a lot of time.


CiviCRM generates valid SMTP emails, so the issue is almost certainly with your mail stack.

I would speak to your mail administrator. If you ARE the mail administrator, I'd download a copy of swaks and send some test emails through Sendmail on the server in question. Ideally, you're running swaks on the server itself, possibly even as your CiviCRM web server user.

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