As a user recently reported an email I sent with an attachment never arrived. Not even in the Spam box. So what happened? Well my first thought is my email was blocked, but no.
Emails without this particular attachment arrived fine. Next thought, the attachment is being flagged and the ISP is trashing it before it gets to the user. Not uncommon and most often seen with Comcast or Verizon. They love to decide if it is Spam before you can 🙂
A user posted to a forum with this concern "I get a message that the mail was sent successfully but it never arrives at its destination. I have checked junk/spam mail folders, and it is not there. I also tried disabling outgoing message scanning, but it makes no difference. No attachments can be sent, regardless of file type, size, or number of attachments per e-mail."
So what to do?
Try sending the file as a zip file attachment. (This has nothing to do with file size but all to do with spam filter scanning). This prevents a lot of Spam filters from scanning the document. Click here to find out how to compress a zip file.
Final Note: Always follow up an email with an attachment with another email, text based. My bad I forgot this best practice, and my client thought I was ignoring them because they never got my email.