Recipients not receiving attachments

Over the past 2 weeks I've had an alarming number of recipients who tell me they aren't getting my attachments. I work in real estate so we send a LOT of PDF files back and forth.

This is a recent development and seems to be occurring with recipients on Gmail, Yahoo, Comcast, etc. so it's not isolated to 1 domain. And yes, I am checking my Sent mail to confirm the attachment was included on my original email.

Not sure if this is a problem on my end with my server?

I'm not super-experienced with cPanel but I do have root access. I have a small biz, so we pay for a cloud-base VPS dedicated host.

 

Just had this happen and I checked the Mail Delivery Report. It confirms the attachment was there.

What are some reasons why the remote server block the attachment?

Also, how exactly would I go about contacting the admins for services like Gmail or Comcast? The only support contacts I can find are for their own customers.

 

After another week of observation, I'm convinced it's MY server that is removing the attachments before processing the email. I am the only sender my recipients are reporting not receiving attachments from. Often, when a recipient tells me they didn't get the attachment, and I re-send it to them, they get it. So if it was a case of the recipient's mail server removing the attachments, that wouldn't be happening.

So I'm still looking for some help here. Is there any kind of cPanel setting that affects mail attachments? Or permissions/memory/drive space allocated for attachments? Or maybe I have an over-zealous security setting that's flagging PDFs? I can't find anything specifically but thought it might be labeled differently.

 

It's both PDF and JPG files. I don't believe we have any 3rd party scripts installed, but I profess ignorance on where to look for that.

 

Please don't laugh, but our server is unmanaged (it's cloud-based VPS hosting through DotBlock). A good friend of mine is an IT professional and he did the initial setup for us. Occasionally he'll check in to make sure everything is running smoothly, but to be honest this is the first "problem" we've ever encountered. Unfortunately my IT friend does everything through the terminal and isn't familiar with cPanel, so I've been trying to educate myself.

And yes, these attachments are being sent through Outlook, specifically Outlook for Mac 2016.

 

Yes, some recipients are getting them just fine, and consistently. Others aren't getting ANY attachments. And others are not getting them in my initial email, but if I re-send them the attachment, sometimes they get it on the 2nd try.

 

Yes, a normal IMAP account. I believe the settings are default.

I tried your Webmail suggestion to email a JPG file to a recipient who had not been receiving my attachments. She did get the attachment, but again, the problem is intermittent.

EDIT: Would Outlook sending through unsecured ports have anything to do with this issue I'm having? I had Outlook set up to use SSL but apparently after upgrading recently it defaulted back to the normal setting and wasn't using SSL. I changed it back to SSL.

 

Thanks for this tip. It's set to "50M" (assuming that's 50 mb), which I would think is plenty sufficient. We try to keep PDF attachments as small as possible, and we even re-optimize and compress PDF's using an app called PDFOptim if the file size is too big.

Most of the docs we send are small -- under 1 mb. In the event we have a whole package of documents to send, the file sizes can get up to 7-8 mb. If they get any bigger than that, I usually just send it via DocuSign, Dropbox, DotLoop or some other service our clients are familiar with.