Can linking to PDF files in email cause bounces due to Mimecast or other security filters?

Email marketer from EmailGeek Forums User PDFExpert states that while PDF attachments can cause bounces linking to files also can do the same if the file is on a unsafe server.

Email marketer from EmailToolTester says that if you link to a blocked or blacklisted site, then yes that is an issue. But generally linking to a PDF is not as big an issue as it used to be.

Email marketer from Mailjet explains that while linking to a PDF may not directly cause bounces, the content within the PDF can trigger spam filters. Also, using link shorteners can negatively affect deliverability.

Email marketer from Email Geeks shares that the issue might be that the links are directly to a Google storage bucket public link, not necessarily the PDF itself.

Email marketer from Gmass explains that it does not matter wether or not you link to the file of include it as an attachment, both can cause deliverability issues.

Email marketer from Hubspot explains that similar to images if the content is not safe the email can be rejected. Even if you link to the image and do not host it directly on the email, it can be rejected.

Email marketer from Reddit user u/EmailPro shares that direct links to PDFs hosted on untrusted or new domains can be flagged as suspicious by spam filters. They recommend using a reputable hosting service and building a positive sending reputation.

Email marketer from StackOverflow user LinkLover shares that the location that you link to is very important, make sure it is from a known reputable provider. Also make sure that PDF is clean and free of malware.

Email marketer from Email Vendor Guide responds stating that linking to PDFs directly shouldn't cause deliverability problems, however the URL and the content of the PDF can be scanned and will cause issues depending on what it contains.

Email marketer from Email Geeks explains he found the cause: Some links on the customer's email are not reachable from certain locations, and he believes Mimecast scanners blocked it.

Email marketer from Sendinblue shares that while directly linking to PDFs isn't inherently problematic, the content and reputation of the linked domain can influence spam filtering. They suggest monitoring sender reputation and ensuring content is relevant.

Expert from Word to the Wise responds sharing that including links to domains with low reputations, or to content that is identified as spam can negatively affect email placement and deliverability, including linking to a PDF.

Expert from Spam Resource shares that linking to PDFs can be problematic if the linked domain has a poor reputation or if the PDF itself contains suspicious content. Spam filters may flag these links as potentially harmful.

Expert from Email Geeks shares that blocking content analysis gateways from seeing the hostile content, while letting the recipients see it, seems like something malware would do. He also notes that the rejection is a generic Mimecast rejection.

Documentation from Google Workspace answers that Google Workspace has limits on attachment and message sizes. Linking to a PDF avoids the size limitations but the link could be checked by security tools.

Documentation from RFC Editor states that RFC specifications define standards for email formats, including how attachments and links should be handled. Non-compliant formatting may trigger security filters.

Documentation from Mimecast Knowledge Base explains that rejections due to security policies can occur when the content of the email (including linked content) violates the organization's configured rules. These rules can be configured to block certain content types or URLs.

Documentation from Microsoft explains that PDFs, like other file types, can be blocked by Exchange Online Protection if they contain malicious content. Linking bypasses attachment filtering but the linked content could still be scanned.