Hi - really hope someone can help, I am quite a novice at setting up Exchange so please bear with me. I have recently installed Exchange 2013, there was some initial failures due to old 2010 Exchange server that died, eventually got to a successful install of Exchange 2013 running on server 2012, so far I can send and receive emails internally no problem, I can receive emails from external email addresses, I just cannot send emails to an external email addresses. I am seeing errors like below when I send to a gmail.com account
Failed to connect. Winsock error code: 10051, Win32 error code: 10051 Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts. The last endpoint attempted was 2607:f8b0:400c:c03::1a:25'
Please help! getting quite desperate to solve this issue.