Cryptic crossword No 4,106

Across

1. Failures in email system regularly lead to spam (6)
2. And what have you ordered the teacher with no husband? (2,6)
3. Characters in Nickelodeon series for a long time (4)
4. Experienced clue writer's colourful device? (4-3,3)
5. Director that is difficult and resistant to change (3-4)
6. Channel One removing content (6)
7. Italian food in largely quiet area (7)
8. Refuse to allow love on screen (4)
9. Dorothy lying about receiving rent support (6)
10. Make weaker police officer haul in delivery (6)
11. Request computer assistance and invite trouble (3,3,2)
12. Last month I uncovered ball to unravel (8)
13. Developing nice tan line, having picked out island for big anniversary (10)
14. Exit from European "dictatorship" originally backed by constituent (6)
15. Country in agreement to stay quiet after fighting war (6)
16. Most stupid person in the country enters exam (8)

Down

1. Len's antique coin sadly of no value (15)
2. Dire Gunners failing to defend header from Rodgers and conceding (12)
3. Returning steel bat I've nicked? Not entirely certain (10)
4. Improvised hit in concert (7,8)
5. One might ultimately stop wrongdoing? (3-2)
6. People drawn towards tornado perhaps produced short screams (5,7)
7. Endure religious studies class – only course left to take? (4,6)
8. US politician's motorcade hiding an old criminal (8)
9. Eager to not have former partner mentioned (5)
10. Rabbi's outside very loudly repeating phrase (4)
11. Flying toy is apparatus on end of twine (4)
12. Complaint from a lot of these touring bottom of the sea, involving nitrogen? (3,5)