Does attaching a PDF to an email hurt deliverability?
Summary
What email marketers say12Marketer opinions
Email marketer from EmailToolTester advises that it's generally better to include a link rather than an attachment, as it avoids large file sizes and potential spam flags. Plus, you can track link clicks.
Email marketer from Web Hosting Talk Forum comments that in the context of promotional emails, attachments are generally frowned upon and will almost always hurt your deliverability rate.
Email marketer from DigitalMarketer responds that sending unsolicited attachments, including PDFs, is a risky practice that can damage your sender reputation and lead to emails being marked as spam.
Marketer from Email Geeks answers that PDF structure matters, recommending PDF spec versions 1.4 or 1.6 without external links or embedded media for deliverability.
Email marketer from Reddit explains that PDF attachments can trigger spam filters if the content inside the PDF looks suspicious or if the sender has a poor reputation. They advise scanning PDFs for malware before sending.
Email marketer from Sendinblue shares that using attachments can decrease your sender score, especially if recipients mark your emails as spam due to the attachment. Using links instead of attachments is generally recommended.
Email marketer from Mailjet explains that while attachments don't directly cause spam filters to flag emails, large file sizes can impact deliverability. They recommend keeping attachments small or using cloud storage links.
Marketer from Email Geeks responds that the linked PDF still needs to pass the desktop AV 'smell test' and be accessible to email servers.
Email marketer from ActiveCampaign responds that sending email attachments can affect deliverability, depending on file type, sender reputation, and content. Malicious files such as .exe, .zip, and .scr are more likely to be flagged.
Email marketer from Quora shares that while not inherently bad, sending attachments (including PDFs) can increase the chances of your email being flagged as spam. This is especially true for unsolicited emails.
Email marketer from Gmass explains that attachments, especially unusual file types can dramatically increase the chances of your email going to spam. Stick to links whenever possible.
Marketer from Email Geeks explains that PDFs aren't universally bad for deliverability and depends on factors like sending reputation, PDF structure, and audience willingness.
What the experts say4Expert opinions
Expert from Email Geeks shares that if the PDF content is the same for everyone, host the PDF so it renders, or better yet, put the content directly on the web and in the email.
Expert from Word to the Wise, Laura Atkins, responds that many filters treat attachments with suspicion and can flag them as spam. Senders should be aware of the potential impact on deliverability.
Expert from Email Geeks shares that there's nothing inherent in a PDF that will cause deliverability problems, even in transactional and CRM mail.
Expert from Spam Resource explains that sending attachments can affect sender reputation, and therefore deliverability. They recommend avoiding sending attachments to large lists unless absolutely necessary.
What the documentation says4Technical articles
Documentation from RFC Editor explains that while RFC 5322 does not set a specific maximum message size, exceeding reasonable limits may cause issues with relaying and delivery.
Documentation from Cisco states that their Email Security Appliance has configurable limits on file sizes that can be scanned. Exceeding these limits leads to a higher spam score and potential delivery delays or failures.
Documentation from Google Workspace Admin Help shares that Google Workspace has a size limit of 25 MB for attachments sent through Gmail. Larger files need to be sent via Google Drive.
Documentation from Microsoft Exchange responds that the maximum default attachment size is 10MB. However, this can be configured at the server level by the administrator to suit various use cases.