Signup for mailgun. You modify your mx/spf/dns records of your domain to use their service. From their site you can create "routes" or forwards from a single address to another, or from one address to 2 addresses.
Mandrill will let you send PDF attachments via their API, but their web composer doesn't seem to allow for uploading attachments.
We use them for sending PDF files, and use their API to take an online-accessible PDF and attach it to an email.
Another alternative, worth looking into, would be Mail Gun. They make it pretty easy to send email as well. I'd say sign up for both (they both have free tiers) and see if either fits your needs.
Gmail changed it smtp server policy recently, you now need your own SMTP server.
I recently setup an account at http://mailgun.com which allows me to use their smtp server to add my domain emails to my Gmail account. Free to 10,000 emails or something like that... set up very easily.
I would use something like MailGun so that he isn't using sendmail/postfix on the server. They do 10,000 emails/mo for free. You can simply send the data over a curl request. It's rather straight forward and language agnostic.