The mail is from “Greatfather Winter” and toy “Winter Veil Disguise Kit”. I have learned it many years ago i guess.
I can’t loot it because “You can’t carry any more of those items”, and I can’t delete the mail because “You can’t delete that” error comes.
Not sure if i managed to change my forum character correctly now, but the issue is on my main druid (Zaflis). Haven’t checked other alts yet but i’d guess this is a more global scale issue than just mine.
Open your mail, take the item into your bags then delete ? If it still doesn’t work, enjoy the duplicates 
You already have one in your bank or bags, delete it and get the one from the mail, then you can delete that too.
Uh, it seems i didn’t have it in my bags but it was in bank. Case closed.
That is good to hear. Thanks a million for letting us know. Glad to hear it got sorted for you.
Kind regards
What’s your opinion?