Emailing a reference letter in PDF to myself. At the bottom of the reference letter are contact details with an email address. When I re-download the PDF and view it, the 'a' within the '@' of the contact email address has been filled in with black ink. This only shows up after I have emailed it. When I view the PDF before emailing it, the @ looks normal. Please help
There is absolutely nothing that is done to the internals of a PDF file when sent as an attachment to an e-mail.
What are you viewing the PDF file with when you receive the e-mail with the attachment? In both cases, are you using Acrobat or Adobe Reader or are you using a viewer built into the e-mail client? If the latter, try reading the PDF file attachment with Acrobat or Adobe Reader! Many third party PDF viewers are somewhat problematic in terms of adhering to the PDF specification and dealing with fonts.
BTW, what font is the ‘@’ character formatted with and is that font embedded in the PDF file? We'd also be interested in knowing what platform (i.e., operating system) you are running under and what e-mail client you are using (Outlook, web browser e-mail, etc.).
Did you make an outline of the font (which should not be done) or is the font still alive?