This one gives me an error :
"Applescript error : parameter "class pmar" missing for "event emalcpma" "
number -1701 partial result «handler «event emalcpma»» from «class pmar»
And yes, MBPHD is my boot disk.
EDIT : after a reboot, the scripts runs but fails to save the attachments.
I selected one mail in Mail, with 5 pictures attached, and ran the script from Applescript editor.
Result :
count every mail attachment of message id 27700 of mailbox "Valérie-Olivier"
--> 5
get name of item 1 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier"
--> "IMG_6833.jpeg"
save item 1 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier" in "MBPHD:Users:bruno

ocuments:Attachments:IMG_6833.jpeg"
--> error number -10000
get name of item 2 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier"
--> "IMG_6835.jpeg"
save item 2 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier" in "MBPHD:Users:bruno

ocuments:Attachments:IMG_6835.jpeg"
--> error number -10000
get name of item 3 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier"
--> "IMG_6832.jpeg"
save item 3 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier" in "MBPHD:Users:bruno

ocuments:Attachments:IMG_6832.jpeg"
--> error number -10000
get name of item 4 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier"
--> "IMG_6840.jpeg"
save item 4 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier" in "MBPHD:Users:bruno

ocuments:Attachments:IMG_6840.jpeg"
--> error number -10000
get name of item 5 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier"
--> "IMG_6842.jpeg"
save item 5 of every mail attachment of message id 27700 of mailbox "Valérie-Olivier" in "MBPHD:Users:bruno

ocuments:Attachments:IMG_6842.jpeg"
--> error number -10000
end tell