Accessing emails on more than one device used to be challenging, as emails would be downloaded to one device, and would not be available on another. You used to end up with emails on different devices, and sent items on different devices too. All very confusing.
If you are in this situation, you are probably one of the many businesses that are still using POP3 email accounts. You should look to move to IMAP, which stands for Internet Message Access Protocol.
E-mail clients using IMAP generally leave messages on the server until the user explicitly deletes them. This and other characteristics of IMAP operation allow multiple clients to manage the same mailbox. For example, access your email on a smart phone and a laptop. If you read an email on your smart phone, then it appears to be marked as read on your laptop when you next login. You could delete the email on your laptop email client software, and it will also be deleted on your smart phone. All your emails automatically keep synchronised to the mail server.
When you setup a new email account, you normally have the option of creating the account as an IMAP account by ticking a small checkbox.
I have several email accounts, which are all IMAP enabled. I access these on my iPhone, iPad, home PC, work laptop, and by webmail too. Some Sunday evenings I quickly read and delete emails from my home PC. This saves me time on Monday morning, as emails are marked as read on my work laptop, and the deleted ones are gone, allowing me to focus my time on the week ahead.
If you’re not using IMAP, speak with your IT support provider, and ask them to explain what is involved in migrating from POP3 to IMAP, and the benefits of doing so.