Email providers do allow fairly large attachments on paper — Gmail caps a message at 25MB and Outlook/Microsoft 365 at 20MB — but a smaller PDF is still worth sending. Large attachments are slower to send and receive, more likely to trip spam filters, and can bump against a recipient's inbox quota well before you hit those hard technical ceilings.
Compress a PDF nowThe gap between an email provider's technical limit and a practical, smooth attachment size is bigger than most people expect. A 25MB Gmail message and a 20MB Outlook message are both allowed, but recipients on a slow connection, a small inbox quota, or an aggressive spam filter can all run into trouble with a large PDF long before the hard cap is reached — and if the attachment fails silently, you may not find out until they ask you to resend it. Compressing to the Recommended preset is a sensible default for any email attachment, regardless of provider.
Most email clients show the attached file’s size — if it is more than a few megabytes, it is worth compressing before you hit send, even if it is technically under your provider’s limit.
Add the file in your browser — compression runs on-device, so your document is not uploaded anywhere before you attach it to the email.
Recommended quality is the sensible default for an email attachment — it shrinks the file noticeably without a visible drop in image quality for the recipient.
Download the result and attach it as usual — a smaller file sends faster and is less likely to be flagged by spam or attachment-size filters.
Getting through the provider’s technical cap is not the whole story — spam filters, the recipient’s inbox quota, and slow connections can all cause problems with a large attachment well below the official limit, so smaller is safer even when it is not strictly required.
There is no single universal number since it depends on the recipient’s provider and connection, but keeping a PDF attachment to a few megabytes after Recommended-quality compression comfortably avoids the most common friction points.
At the Recommended preset, text stays fully sharp and images lose only a small, usually unnoticeable amount of detail — the document remains fully readable and professional-looking.