[Retros] attachments in messages

[Francois Labelle]

Two points:

- The link at the end of the four lines gives information on how to 
unsubscribe from Retros. As much as we like to think that this mailing 
list is awesome, we have to make it easy for anyone to unsubscribe.

- The mailing list adds "[Retros]" to the subject line for easy automatic 
filtering. Technically the best solution is for subscribers (like Andrew) 
to whitelist all such mails. (If that's not possible, then curse your 
e-mail client: how can it have sophisticated spam filtering algorithms yet 
no simple whitelisting feature?)

 	Francois