How to stop Outlook 2016 Valid email addresses being rejected as - Microsoft Community

i using outlook 2016 , windows 10 on acer laptop.

because of overall internet speed issues leaving isp , isp's email service, hence move gmail.

when compose message in outlook , use gmail server message comes server error address cannot found. if resend same message via old isp's server delivered exact same addresses.

i cannot find reason conflict between outlook , gmail in other respects 2 working well. gmail inbox works in outlook.

i had earlier advice g suite forum when setting outlook 2016 use gmail make these settings:

imap

incoming: imap.gmail.com. -----port 993 ----ssl

outgoing: smtp.gmail.com  -----port 465 ----ssl  requires authentification.

if compile message in outlook , send via smtp.optusnet.com.au there no problem. (optusnet being current isp)

i can compile in gmail , send via mail.google.com without problem.

i should able mix them ie compile in outlook , send via mail.google.com or smtp.gmail.com "undeliverable" result.

the error message each address constant.

server error: '553 5.1.2 rfc-5321 address. y78sm12323630pfd.32 - gsmtp' the section in red is not constant.

i assumed server referred google server.

i appreciate help, please

thanks

peter

i checked less secure , on. used gotcha link , logged in again sent message 27 people , bounced back.

but time sender (ie me) not recognised. , server not googles current isp. how weired!

i did again , got same result started getting replies people had received message.

i think techie has been playing tricks on me.

anyway thankyou sticking me . declare fixed (somehow)

Office / Outlook / Windows 10 / Office 2016