How can I tell if someone is able to receive a PM?
Look for an envelope. If they are using an alias like you are it will be an active link but no envelope.
Quick edit here -- you really don't know they can receive the PM in all cases, sometimes you can send but if they don't have an active VIP they cannot read what you sent. If that was your questions, you cannot know.
-- Modified on 1/4/2017 4:25:39 PM
-- Modified on 1/4/2017 4:33:41 PM
So if there's a yellow envelope a hobbyist can or cannot read my PM?
...Only those with a VIP membership (either thru review submission or paymen) can read them.
... providers who have their profiles linked to their handles get free "limited VIP", which includes PMing.
And the other way VIP days can be earned is by filing problem reports--2 VIP days per accepted report.
Also, VIP days can be gifted from one member to another.
So, a few other ways to get full VIP besides submitting reviews or paying for it. 
If her profile says "send PM" then you can.🙂
I didn't know they could be gifted! Cool. How do I start a go fund me for this?
...transferring them from your account to another's account.
If so, then they should have VIP.
I can't think of any other way rather than to ask them on their local board, but I think TER frowns on that
Then they have VIP and will receive PM's. Click the alias on the post.
As was said, if they have recent reviews, then they may well have it. It's 15 days per review, but they are only dated by month, you don't know if it came out on the first or the 31st. Plus, they have three months after the visit to write the review, so all that can be inconclusive a lot of the time. If they have two or more that have gone up within the last month, then they have VIP, at least for now.
Badic members know they got a PM but can't read it. It will be there for them should they eventually upgrade to VIP. The envelope, (which is brown AND yellow) proves nothing.