DatabaseMail didn't start when an email is queued
see what happens when you try to send an email using powershell instead.

$smtpServer = "200.1.1.223"
$smtpPort = 25
$emailFrom = "donotreply@xxxxx.co.uk"
$emailTo = "mmiorelli@xxxxx.co.uk"
$smtp = new-object Net.Mail.SmtpClient($smtpServer)
$smtp.Port = $smtpPort
$subject = "ccatsql" 
$body = "test email from ccatsql " 
$smtp.Send($emailFrom, $emailTo, $subject, $body)


and checked which .Net versions you have installed

the problem might be in the .NET. Check the windows\applications error log.
I had a similar problem (see the question here) then I installed .NET 3.5 and all started to work nicely.



SQL Server 2016 - Database Mail doesn't work without .NET 3.5

How can I see the current Database Mail configuration?

EXEC msdb.dbo.sysmail_help_configure_sp;
EXEC msdb.dbo.sysmail_help_account_sp;
EXEC msdb.dbo.sysmail_help_profile_sp;
EXEC msdb.dbo.sysmail_help_profileaccount_sp;
EXEC msdb.dbo.sysmail_help_principalprofile_sp;

EXEC msdb.dbo.sysmail_help_account_sp


Have a look at this question and answer:
Comprehensive troubleshooting of DatabaseMail