Do PDF attachments negatively impact email deliverability and what are the best practices?

Email marketer from Gmass explains that attaching files can increase email size and trigger spam filters, therefore they recommend linking to the PDF instead.

Email marketer from Hunter.io recommends to always compress attachments and consider sharing files via cloud storage services like Google Drive or Dropbox.

Email marketer from Mailjet Blog explains that attaching PDFs directly to emails can negatively impact deliverability due to increased email size and potential triggering of spam filters. They recommend hosting the PDF on a website and linking to it within the email.

Email marketer from Email Geeks shares it's much better and easier to host the PDF on a publicly accessible server and then linking to it from inside of the email.

Email marketer from Email Geeks shares they would always suggest hosting the file somewhere and providing a link to it (if the pdf is not customized for each recipient, at least) to reduce the carbon footprint of your emails, by not sending MBs over the Internet, and storing them in the mailbox of the recipients.

Email marketer from Reddit shares that PDFs can sometimes trigger spam filters, especially if they contain unusual content or are unusually large. Linking to the PDF is a safer option.

Email marketer from Quora responds that it is a better user experience to link to a PDF to avoid the customer having to download it first.

Email marketer from Woodpecker explains that it's generally better to link to the file if it's large and include a summary of what the link is about in the email body.

Email marketer from Email Geeks shares there is no direct impact on deliverability, but it can have an impact on your infrastructure (DKIM-signing a 4MB attachment for 500K recipients, will hurt) and it can hurt CPU, so servers could be busy, be slow, crash.

Email marketer from Email Geeks explains they've attached pdfs to transactional emails in the past and stopping this didn't have a material effect on deliverability but best practice not to do that if you can at all avoid it.

Email marketer from StackExchange explains that problems with pdf attachments include increased email size and potential flagging as spam.

Email marketer from Email Geeks shares that attaching PDFs will definitely wreck your delivery rates, as email clients will see it as a red flag for potential spam and malware.

Email marketer from Sendinblue Blog shares that instead of attaching files to emails, it’s better to include a link to the file, for a better experience and email size.

Email marketer from Campaign Monitor Blog explains that large attachments can trigger spam filters, slowing down delivery, or preventing your message from being delivered at all. They recommend using links to files hosted online.

Expert from Word to the Wise explains that using attachments in emails, especially unsolicited ones, is a bad practice and can harm your reputation. Providing a link to the content on your website is a preferred method.

Expert from Email Geeks shares that you have more control when directing people back to a website, you can see who's actually requesting them and you can have them expire. Lots of benefits to not just putting them on the email (where you won't even get to register a click for engagement).

Expert from Spam Resource explains that large attachments can lead to emails being rejected or delayed, they recommend checking the limits for file sizes on your email and recipient servers.

Expert from Spam Resource explains that using attachments can impact spam scores and advises scanning outgoing mail for potential malware, and also provides a list of bad attachment types that impact spam scores.

Documentation from Litmus explains that overly large emails, often caused by attachments, can increase the likelihood of being flagged as spam. They suggest optimizing attachments for size or linking to them instead.

Documentation from RFC2476 specifies that message size is a major factor in deliverability, with some servers rejecting large emails. PDFs increase the overall size of emails.

Documentation from MXToolbox explains that attachments can increase your spam score because malicious users may be tempted to disguise malware as an invoice, statement, or order confirmation.

Documentation from Google Support explains that Gmail has attachment size limits and recommends using Google Drive for larger files. Exceeding size limits can cause delivery issues.

Documentation from Microsoft Support details attachment size limits in Outlook and recommends using OneDrive for larger files. It says using attachments that are too large can prevent emails from being sent.