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APD TorontoFlag for Canada

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PHP Mailer Not Sending to Some Recepients


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I’m testing sending out automated emails from but not all are going through. For example, when I send to I get “..mailbox unavailable or not local…”.

Please ignore “email sent” in this instance, because I quickly wrote the script without any error testing. However, it is sending to the following (hosted by Microsoft, also mailbox is not local, but working) (hosted by Google, not local and working)

One thing that I found strange when receiving the credentials for as user is that said that if I want to encrypt emails, I need to purchase SSL. I know usually the SSL is for the server side, not client side. I am thinking that maybe that the is some type of a budget server, but I cannot see how this relates to my script, which is at another server, and it should come down to sending a regular email. Manually, you are  able to email

What could it be?
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Ryan Chong
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some mail servers will only allow whitelisted domains before the emails can reach them.
for encrypted mail s/mime you need a certificate attached to your email address.. then you and the recipient need to send a signed message to each other so you both have the others private key. You then can send encrypted s/mime mail 
@APD Toronto,

If those are valid emails you might want to redact them or at least make your question private.

What you are experiencing is a common problem and has nothing to do with your code but rather the server you are sending from.

Best advice going forward - use a Mail service provider (like MailGun) - one that is professionally focused on server reputation and email delivery.
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APD Toronto
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