This appears to be a security issue. I suggest a scan for malware that is intercepting your email.

Start computer in Safe mode and then perform a scan.

After performing scan and all is ok.....Logon to the webmail account and check to see if other email addresses have been added to the account or whether the settings to auto forward emails to another address have been created. I would also suggest you change the password whilst in webmail account.

Also check your Account Settings to see if you have an additional identities for the mail account.

Check your Address book to see if you have any contacts in any of the address books that match the problem email address.

Go to your compose window and start composing a new mail to yourself. Once you have added the email address to the email, do you see just your name, or your name plus the email address you are sending the email to?

Thanks Matt As soon as I start entering my own address to send the email to myself, I get a short list of options to click. The first one is my own email address in blue, accompanied underneath in grey by a phantom address which is tied to it. If I send to my address I do not receive it, therefore I assume it is going to the phantom. I have searched my contacts to see if the phantom appears but there is no sign of it.

This only happens when sending from my mobile phone and not when I send from my laptop.

re :This only happens when sending from my mobile phone and not when I send from my laptop.

This forum is for Thunderbird on desktop/laptop not mobile phones.

Are you saying your problem is only occuring when you use phone? Do you have Thunderbird for Android on phone ?