Mate of mine, UK ATPL, 3000hrs, B757 current. Told by Delta that they would take him provided, of course, he got his FAA ATP and had the right to live & work in the USA. He told Delta that it would smooth things with the Immigration bods in the UK if he could have a formal letter offering employment. Delta told him, no, first, you need your green Card. US immigration in the UK said they would give him a green card if Delta gave him a formal job offer. My mate asked if Delta and US immigration people would talk to eachother. They never did and stopped talking to my mate as well. That was in 1985.