emails not arriving

[rao4844]

Person 1
ISP: BT Broadband
email address 1: person1@btconnect.com
email address 2: person1@gmail.com

Person 2
ISP: Sky Broadband
email address 1: person2@sky.com
email address 2: person2@gmail.com
email address 3: person2@btinternet.com

This is the problem.

Person 2 can send emails from any of his three email accounts to all his own email accounts and both email accounts of person 1.
All emails are received.

Person 1 can send emails from both his email accounts to both his own email accounts and the three email accounts of person 2.
However, emails are received in the two accounts of person 1 and the three accounts of person 2 only when person 1 uses his gmail account.
Emails are received in both accounts of person 1 but only in the btinternet account of person 2 when person 1 uses his btconnect account.

Has anybody any ideas why the gmail and sky accounts do not receive the emails when person 1 uses his btconnect account?

 

[rao4844]

Problem solved.
The emails from person 1 using btconnect had been treated as spam by the gmail and sky accounts of person 2.
Person 2 had not picked this up because he had been reading his emails in outlook express and his gmail and sky accounts did not forward any spam emails.