I'm involved with a campaign to remove bad backlinks for which the clients google ranking is penalized.
There is are three parties involved; me, an SEO company based in Dehli, India and the Client. The SEO company requested email login credentials so as to send the Link Removal Requests from firstname.lastname@example.org, but the client doesn't want to release the info for security reasons. They suggest sending from webmaster@ and they will forward responses.
I had initially sent a few link removal requests from a gmail account with good results from anyone who responded.
Possibly email@example.com or firstname.lastname@example.org - and sending via mail.client.com would be the most sensible.