Email sending not working

HI,

When trying to configure on-premise sentry mail sending fails for some reason.

In the worker logs I see the following:

worker_1                   | SMTPConnectError: (521, 'Disallowed host')
worker_1                   | 14:46:36 [ERROR] celery.worker.job: Task sentry.tasks.email.send_email[8ae9e273-200e-4fd3-ac06-5cb53e45ab21] raised unexpected: SMTPConnectError(521, 'Disallowed host') (data={u'hostname': 'celery@6e2903faed67', u'name': 'sentry.tasks.email.send_email', u'args': '[]', u'internal': False, u'kwargs': "{'message': <django.core.mail.message.EmailMultiAlternatives object at 0x7fcc897baf50>}", u'id': '8ae9e273-200e-4fd3-ac06-5cb53e45ab21'})

I’ve several other containers on same machine (and on other machines as well) that can send email without problems so do I need to configure something else beyond SMTP settings in config.yml?

Apparently tried to use wrong SMTP server on wrong network.