When composing you add an email address into To field. Is the email address correct at this point ? After you enter each email address, does it change to a 'pill' - each email address is separate in it's own outlined box ?

In 'Address Book- Do you have any incorrect email addresses for the people you are trying to send an email? Please note: check using the 'All Address Books' option and select to sort by 'Name' and then also try sorting by Email. For example you may have two entries for JJJ@msn.com Both might have same Name, so you can see if there are two entries for that name. The entries may have different 'Name' but might show under Email like this - one following the other. JJJ@msn.com JJJ@msn.comNNN @yahoo.com

Do you have any 'mailing lists' in an address book which has the contact JJJ@msn.com? For example - is JJJ@msn.com in a mailing list?

re :Deleted the emails from the address book. Failed, they added back in. Did they have incorrect data? Can you see there is a bad email address? What address book are you talking about ? Is it a Thunderbird default address book like 'Personal Address Book' or 'Collected Addresses' ? Is it a gmail address book ?

Regarding a Mac OS X Address Book - does not apply to you but I've included it just in case someone using a MAC sees this question. Some address books cannot be edited via Thunderbird. eg: Mac OS X Address Book - you have to edit by opening that address book Where do I find my address book on MAC? Open the Contacts (10.8) or Address Book (10.7 and 10.6) application. Normally, these will be located in your Applications folder.

Toad, Thank you for your reply. My responses inline.

When composing you add an email address into To field. Is the email address correct at this point ? Yes and there is no other email than those that I entered.

After you enter each email address, does it change to a 'pill' - each email address is separate in it's own outlined box ? Yes

In 'Address Book- Do you have any incorrect email addresses for the people you are trying to send an email? Please note: check using the 'All Address Books' option and select to sort by 'Name' and then also try sorting by Email. For example you may have two entries for JJJ@msn.com Both might have same Name, so you can see if there are two entries for that name. The entries may have different 'Name' but might show under Email like this - one following the other. JJJ@msn.com JJJ@msn.comNNN @yahoo.com

I do not have an incorrect email in the address book. I do not have 2 entries for any of the bad emails. I have tested deleting the bad emails from the address book and then sending an email. Then when I do send an email. Not to any of the bad addresses. I get the three error messages and the bad emails are added back into my address book.

Do you have any 'mailing lists' in an address book which has the contact JJJ@msn.com? For example - is JJJ@msn.com in a mailing list? No.

re :Deleted the emails from the address book. Failed, they added back in. Did they have incorrect data? The JJJ@MSM.com is incorrectly formatted. Can you see there is a bad email address? Yes

What address book are you talking about ? Is it a Thunderbird default address book like 'Personal Address Book' or 'Collected Addresses' ? Is it a gmail address book ? It is the Thunderbird address book.

re: What address book are you talking about ? Is it a Thunderbird default address book like 'Personal Address Book' or 'Collected Addresses' ?

It is the Thunderbird address book. Which one? 'Personal Address Book', 'Collected Addresses' or one you created or imported ?

I'm a bit confused...please clarify: You say there are no bad email addresses in any of your address books. I do not have an incorrect email in the address book. I do not have 2 entries for any of the bad emails.

So you deleted the contacts that had those good email addresses - which address book did you delete them from? Personal Address Book' or 'Collected Addresses' ?

Then you say: I get the three error messages and the bad emails are added back into my address book. This means you do have bad email address stored in the Address Book. It also suggests they are being automatically added because they were not in any address book. What address book have you set up to auto store sent emails?

• Menu icon > Preferences > Composition
• Under 'Addressing'
• Is this selected 'Local Address Books'
• Is this selected : 'Automatically add outgoing email addresses to my'
• If yes, what address book is selected ?

Check to see if there are any 'Display' that has an email address like example below.

example: I'm wondering if you have: a Contact with a 'Display' entry that has eg: JJJ@msn.comNNN @yahoo.com OR a Contact with a 'Display' entry that says: JJJ@msn.com and it's email address that says: NNN @yahoo.com

As this error occurs no matter what email address you are sending TO : eg: Sent three emails TO

• NNN@yahoo.com
• ABC@btinternet.com
• XYZ@gmail.com

Do you notice part of the error is always the same eg: is JJJ@msn.com always inserted before name you sent to?

• Please check the message recipient ""JJJ@msn.com NNN"@yahoo.com"
• Please check the message recipient ""JJJ@msn.com ABC"@btinternet.com"
• Please check the message recipient ""JJJ@msn.com XYZ"@gmail.com"

I have seen an error that was similar. In the Address Book for a contact, the person had accidentally inserted a space before the email address. This is not exactly easily noticeable, but can occur if you copy pasted in an email address and included a space. On that occasion the person had a Contact something like this: Display: PETE Email: peter@adomainname.com I need you to pretend a space was put just before the 'peter' in email address. The result caused this: PETE <"peter"@adomainname.com>

In Account Settings have selected the following: In Account Settings select the name of the account. On the right near the bottom have you selected this: 'Reply from this identity when delivery headers match' and entered email addresses ?

re: What address book are you talking about ? Is it a Thunderbird default address book like 'Personal Address Book' or 'Collected Addresses' ? Personal Address Book

It is the Thunderbird address book. Which one? 'Personal Address Book', 'Collected Addresses' or one you created or imported ? Personal Address Book

I'm a bit confused...please clarify: You say there are no bad email addresses in any of your address books. To test, before I sent an email, I check the personal address book and delete any of bad the addresses, I then send the test email. I then get the 3 errors. All the bad addresses are back in the personal address book.

So you deleted the contacts that had those good email addresses - which address book did you delete them from? Personal Address Book' or 'Collected Addresses' ? Personal Address Book

Then you say: I get the three error messages and the bad emails are added back into my address book. This means you do have bad email address stored in the Address Book. It also suggests they are being automatically added because they were not in any address book. What address book have you set up to auto store sent emails? Collected Addresses

• Menu icon > Preferences > Composition • Under 'Addressing' • Is this selected 'Local Address Books' • Is this selected : 'Automatically add outgoing email addresses to my' If yes, what address book is selected ? Collected Addresses

As this error occurs no matter what email address you are sending TO : eg: Sent three emails TO • NNN@yahoo.com • ABC@btinternet.com • XYZ@gmail.com Do you notice part of the error is always the same eg: is JJJ@msn.com always inserted before name you sent to? No, When I send any email, from any account, I always get the same errors in the same order.

'Sending of the message failed. An error occurred while sending mail. The mail server responded: Administrative prohibition. Please check the message recipient ""JJJ@msn.com NNN"@yahoo.com" and try again.''

Then I get the same error 2 times: 'Sending of the message failed. An error occurred while sending mail. The mail server responded: unrouteable address.'

Please check the message recipient "e555@anycompany.net" and try again. • Please check the message recipient ""JJJ@msn.com NNN"@yahoo.com" • Please check the message recipient ""JJJ@msn.com ABC"@btinternet.com" • Please check the message recipient ""JJJ@msn.com XYZ"@gmail.com"

I have seen an error that was similar. In the Address Book for a contact, the person had accidentally inserted a space before the email address. This is not exactly easily noticeable, but can occur if you copy pasted in an email address and included a space. On that occasion the person had a Contact something like this: Display: PETE Email: peter@adomainname.com I need you to pretend a space was put just before the 'peter' in email address. The result caused this: PETE <"peter"@adomainname.com>

I checked and there are no spaces in the email addresses.

In Account Settings have selected the following: In Account Settings select the name of the account. On the right near the bottom have you selected this: 'Reply from this identity when delivery headers match' and entered email addresses ? No