I can send a recipient an email with an attachment. I have tested sending both excel and pdf attachments. The recipient receives the email from me and it shows the paperclip indicating that the email has an attachment. However, when the user opens the email, there is no attachment to be found. To make this problem even more strange, if the user then forwards that email to themselves, the new email will have the attachment and they can open it and view it correctly. This recipient is using Outlook 2013 as their email client. It should be noted that when this recipient checks their email on their android phone, or their webmail, that the attachment shows up just fine. It is only in Outlook that this problem occurs. I have done some research and found the inline attachment problem that many have had in the past. However, when I checked the mail.content_disposition_type option in the config, it was already set to 1. I tried setting it to 2 because one forum recommended that setting. That did not fix it either. So if this problem is an inline attachment problem, then maybe there is another setting in this new version of Thunderbird that needs to be changed. As noted in the subject above, I'm using version 38.3.0. It appears this problem just started with this latest update. I'm not positive of that, but I know this problem didn't start until a few weeks ago, and the only thing I can think of that may have caused it would be a new update to Thunderbird. Thank you for your help.