Emails containing dropbox links not being received

Hey Walter, I'm not sure which plan, but it is a business plan and we have 4.9 TB of space left on it, so I'm all clear for space.  As for steps, it's not me taking them, it's someone else (on the same plan) sending me an email with a Dropbox link.  They can send me the email with a Dropbox link, but I never see the email, it is not in any extra junk or bulk mail.  If i send them a link, and they forward me my own message, I will not receive it back.  I'm not sure why this keeps happening.

Someone else in my company cannot receive the emails with Dropbox links either.  We do not have anyone blocked, we do not have any emails filtered, they are just non-existent.

Thanks for the extra details, Cheyenne_integrityav!

Can you let me know when this started happening approximately? Did you always have this kind of issue, or did it occur recently?

I really can't easily provide that unfortunately, but I can walk you through the process.

1. You "share" a document to create a link. The link ends up having a lot of seemingly random alphanumeric characters in it, as always.
2. You then paste that link into an e-mail or a calendar invite and send it.
3. The e-mail or calendar invite goes nowhere -- it seems to send, but is never received by the recipient.
4. THEN, you run that same link through something like tinyurl.com (which changes the link to something else).
5. You paste the link from tinyurl.com into an e-mail or a calendar invite and send it.
6. The recipient gets the email.

So basically, some of the links being generated by DropBox seem to be getting flagged as potentially harmful links based on the characters within the link. I've verified that it isn't happening within any filters in my client's Office365 mail system (or at least, I can't find any filter that might be doing that, and the DropBox-related messages do not show up on any alerts in the O365 admin center), and in some cases the recipient is within the organization (so it's mailing from and to the same mail server, and yet is still getting blocked by something in the middle somewhere).

I don't have an example of the affected links because my client wasn't able to e-mail them to me, as described above.

Some links generated by DropBox work, but somewhere between a third and half of the links they generate do not (to the point where they just always include using tinyurl.com as an extra step in the process of sharing links).

Hey lenpal, thanks for all the information you've shared with us so far. 

Does this happen only when Dropbox shared links are included in the emails or with other links from other sites as well?

Hi Hannah,

This only happens with DropBox links (and as I said, only some of them).

Thanks,

L.

Thanks for the update, lenpal.

Does your client perhaps have some kind of security app like an antivirus, firewall, browser extension that might be affecting this?

No. I was very thorough in checking for any type of security software, O365 rules/filters, etc. before reaching out here.

Hi lenpal, as this appears to be related to the software being used, which is somehow preventing the Dropbox links from appearing normally, I'd recommend contacting the developer of that app for further assistance on this matter. 

Jay, Dropbox is the developer of the app at the root of the problem.

Look, I get it. I ran tech support teams for more than a couple of software companies over the years, so I recognize the instinct to point at some other program and say "go ask THEM". But in this case, the issue is very distinctly within Dropbox, at least in the respect that it is generating links with characters that are getting flagged somewhere as potentially harmful, resulting in messages being blocked. 

Here's the simplest way to identify the root cause:

* Email with link from Dropbox gets blocked.
* Email without link from Dropbox (by masking the link using tinyurl.com) doesn't get blocked.

I don't really expect that Dropbox will fix this problem, but it's most definitely a Dropbox problem. 

Thanks (kind of),

L.

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lenpal wrote:

I was very thorough in checking for any type of security software, O365 rules/filters, etc. before reaching out here.

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Your O365 admin can sign in to their Exchange admin panel and run a mail trace on both your mail account and the recipient's, and determine what is happening with the message.