Is your contact using Thunderbird? Is the third party using Thunderbird? Are the attachments actually received by the third party? Can the third party open the attachment using webmail? What type of attachment are you talking about..an image, a pdf or .doc document etc? The third party must have the appropriate software to be able to view the attachment. Their computer must be set to allow opening of attachments. A yahoo website says 'enabling SSL in your Mail Settings often resolves problems with attachments'. To be honest the third party has the issue and it is they who need to ask the question in this forum assuming they are using Thunderbird. There are too many variables and unknown facts to hypothesise on what could be wrong. A link to a Windows help on not being able to open attachments: * http://vlaurie.com/computers2/Articles/when-you-cant-open-email-attachment.htm If using OE or Outlook then perhaps this link may help: * http://askleo.com/why_cant_i_open_attachments_in_outlook/