Just a " heads Up " the Original Poster was saying he had " 301 domains linking to his site, not that he has a domain 301ing to his site "
I've just come from this area for a recent client, Luckily for me it was only 700 urls total.
**I got all the links linking back to my site ( backlinks ) from: **
- Google Webmaster Tools ( Search console )
- Moz.com
- Ahrefs.com
- SEMrush
Added them all to a spreadsheet, downloaded an addon in google sheets called "remove duplicates" to remove same urls, once that was done, I put as much information for these urls as I could find, both what was already listed from those sites I got the backlinks from. Then I also went and visited every single one of them, listed if they were still working or 404, what the anchor text was, what the domain authority and page authority was and anything else to help, like was it a foreign site or a directory listing or comment spam.
I had over 75% of my backlink profile was nofollow or was a directory / comment spam.
So far I have disavowed 153 urls, I have more but want to do chunks at a time so if something really horrid and unforeseen happens I can reavow ( yes thats a real thing ) the urls a section at a time a wait.
I recommend doing this once to create a master backlink list, and just keep things dated and correct so you only have to add to it each month and keep up to date on your backlink profile!
Since backlinks are on par with content in terms of ranking there is no reason to not be so involved with backlinks.