Email on multiple devices

[someone]

I have what must be a common problem with email read repeatedly on multiple devices and wonder how others deal with it. I suspect imap is part of the answer (which I am new to) but need some advice on how to implement.

I use 3 devices:
A.  Laptop using Thunderbird for email.
B.  Tablet using Aquamail
C.  Phone using Aquamail

My isp offers both pop and imap, as well as a browser webmail interface.

Requirements:
1. I need to keep my emails on my laptop, not on the server which has limited storage available. So I use pop3 in Thunderbird on the laptop which works fine.

2. I want to read emails on both the tablet and phone without having to reread and redelete the same emails 3 times. After reading an email on the tablet or phone, I want

      2a -  to have it marked as "read" when it downloads on the other 2. Is that possible with imap?

      2b -  if deleted as junk mail have it deleted on the server too. I know that imap can do that.

I think I can do all the above by accessing my email on the tablet and phone using a browser webmail instead of Aquamail.

Can I do that via Aquamail too? How exactly?

What are the disadvantages of simply using a browser webmail interface to access my email on the tablet and phone?

[someone]

Thank you very much Paris Geek. I appreciate the help.

I use 6 mailboxes (ie. 6 different email addresses) on 3 private domains I own. I don't use Gmail (except for the compulsory one needed to run an android device) but don't use it for email for privacy concerns.

You are correct about the webmail interface. It is a nuisance to access one mailbox at a time. I use webmail sometimes to delete the spam folder contents on the server because the server spam folder does not appear in Aquamail, unless I'm not doing something correctly.

I'm new to imap having only used pop since it was first invented. (I go back to using the Apple II when it was first sold without even a hard drive, and all the models since). The use of tablets and phones is forcing me to use imap.

One problem I have is that when I read email, there are some that are just junk. These need to be deleted forever. This one is easy to setup in imap.

But, there are others I want to delete from the tablet /phone because of their limited space but want to keep on the server for later download to the pop laptop. But these "read" emails will download a second time in the other device, without any indication they have already been read, causing them to be read again before their final download to the laptop, when they may get read a 3rd time!  What a waste of time. (I get hundreds of emails a day). How do you handle this part? That is where I am stuck.

Merci.

[someone]

Thank you very much for your detailed instructions. It is very kind of you to take the time to do all this. I will follow your advice and see how things go.

Thank you again.

[Kostya Vasilyev]

@Paris Geek - thank you so much for your detailed responses.