Emails on iPhone

[HolmesLane]

I have an iPhone and it has BT email, the old Yahoo/BT email and, of course, iCloud.

The phone seems to be confused with BT and Yahoo. Is it safe to delete the Yahoo account from the phone? Would any emails sent or showing as received on it be safely stored in the BT account now? Both show when I try to send an email.

[licquorice]

Is it a vanilla Yahoo account or BTYahoo? If the former, it has nothing to do with BT and the emails are entirely separate. If the latter and both the old and the new accounts are configured as IMAP, the mail is on the BT server which is the same account regardless of which account on your phone you accessed it from.

[HolmesLane]

Thanks for responding. It is the old BT account when dealt with by Yahoo, so not a standalone Yahoo. I was going to check the emails and make a backup (using a laptop) but I couldn't get into the details for the Yahoo account to check the settings. Pretty certain it is IMAP.

When sending messages, it looks like they go out via Yahoo but it shows in the sent box on BT. 

What will happen to the contacts and calendars, which appear to be in the Yahoo account? How can they be moved to BT?