Email with attachments

A PDF is not one of Outlook’s normally blocked attachment types, so first run a controlled delivery test and have the sender check whether Outlook.com accepted the message or returned a rejection notice.^1^

1. Run a delivery test

Ask the sender to send three separate messages:

1. A plain-text email without an attachment.
2. A plain-text email with a small, newly created PDF named test.pdf.
3. The original email and PDF.

This distinguishes a general receiving problem from filtering triggered by the original message, filename, size, or PDF contents.

• Only the original fails: Ask the sender to rename the file simply, remove links/signatures from the message, and resend it as plain text. PDF-containing messages can sometimes be rejected by spam filtering based on their combined content.^2^
• Both PDF tests fail: Ask the sender to upload the PDF to OneDrive and send a sharing link instead. Microsoft recommends this when an attachment is blocked.^1^
• All three fail: Continue with the receiving checks below.

2. Check where Outlook.com placed the message

In Outlook on the web:

1. Open Junk Email, Other, and Deleted Items.
2. Set Filter → Sort → Date so the newest messages appear correctly.
3. Open Settings → Mail → Rules and look for rules that move or delete mail.
4. Check Settings → Mail → Forwarding for unexpected forwarding.
5. Under Settings → Mail → Junk email, check whether the sender is blocked.

If the message is in Junk, right-click it and select Mark as not junk. These are Microsoft’s recommended checks when a specific message is missing from Outlook.com.^3^

3. Ask the sender for the delivery result

If the sender received a non-delivery report or “bounce,” obtain its complete error text:

• An error mentioning spam, blocked content, or a 550 5.7.x code indicates rejection during mail delivery. The sender should remove links/signatures, use plain text, or send a OneDrive link.
• Mailbox full means storage must be freed before another test.
• If there is no error, the sender should use Outlook.com Sender Support, as recommended for a specific missing message.^3^

4. Verify Outlook.com storage

Open Settings → Account → Storage. If Microsoft cloud storage or the mailbox is full, Outlook.com cannot receive email; messages sent while storage is full are bounced and cannot be recovered. Free space, then ask the sender to send the PDF again.^3^

If storage is available, the test PDF is also rejected, and no rule or blocked-sender entry explains it, select Help in Outlook.com, describe the failed delivery test, and scroll to Still need help? → Yes. Include the sender’s address, sending time and time zone, PDF size, and complete bounce error—but do not post that private information publicly.

References

1. Blocked attachments in Outlook | Microsoft Support
2. My outlook messages are being rejected by the receiver if I have an attachment on it. - Microsoft Q&A
3. Can't send or receive email in Outlook.com | Microsoft Support