Hi ​@LuciaRosa, 

That message is usually related to the email account or device's security/administrator settings, rather than your mobile network.

If this is a work or school email account, your organisation's administrator may have disabled access to attachments on mobile devices. In that case, only the organisation's IT administrator can remove the restriction.

If it's a personal email account, try:

• Signing out and back into the email account.
• Checking whether attachments can be opened through the email provider's website in your mobile browser.
• Updating the email app and your phone's software.
• Removing and re-adding the email account to your phone.

If you tell me which email service you're using (for example, Outlook/Hotmail, Gmail, or a work email) and whether you're using an iPhone or Android, I can give you the exact steps.

Owethu