enable database mail

sp_configure 'show advanced options', 1;
GO
RECONFIGURE;
GO
sp_configure 'Database Mail XPs', 1;
GO
RECONFIGURE
GO

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to keep an eye on the emails going in and out, what is failing, try these (found at databasdsournal.com)

sysmail_allitems – This view allows you to return a record set that contains one row for each email message processed by Database mail.

sysmail_event_log – This view returns a row for each Windows or SQL Server error message returned when Database Mail tries to process an email message.

sysmail_faileditems – This view returns one record for each email message that has a status of failed.

sysmail_mailattachments – This view contains one row for each attachment sent

sysmail_sentitems – This view contains one record for every successfully email sent

sysmail_unsentitems – This view contains one record for every email that is currently in the queue to be sent, or is in the process of being sent.
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to clean up messages:
sysmail_delete_mailitems_sp – This SP permanently deletes email messages from the msdb internal Database Mail tables

sysmail_delete_log_sp - This SP deletes Database Mail log messages