We have a client that we are doing pure internal comms (i.e. the mailing list is purely their staff), in a bid to raise the open rate they would like to be able to make the e-mails be sent with a priority indicator on them. Is something like this possible ?
FYI - yes we will be experimenting with titles, A/b testing etc - but we know that their e-mail client highlights priority mail in red.
This is not possible through Campaign Monitor I'm afraid and to be honest, I doubt it is something we'll ever look at implementing.
You're right to give all the testing a go, there was an article on our blog just this week about some tips that might be useful:
Now this is more about click rates, but I think it's interesting to think of alternative ways of doing things. You never know what might work for your group of subscribers.