Unable to send email on android overseas

I've seen this question asked a million times but not answered.

In a foreign country (the Netherlands, Belgium, the Czech Republic, Italy, ...)

Connected via WIFI or 4G, doesn't matter. 

Sending from an IMAP client (tho' the outgoing server is smtp.cox.net, is there any other option?) on my android, the mail sits in the outbox saying failed.  Returning to the states, the email sends.

Using webmail.cox.net (redirects to idm.west.cox.net/coxlogin/....blah blah), I get a capcha (click I am not a robot) followed by a required entry of last 4 of SSN.  Sending an email here fails with

Message could not be sent....

(550-550 146.20.112.67 blocked ....)

AUP#CXBL

I understand that Cox bluntly blocks seemingly all foreign IP to prevent spammers and I can request a white list on an IP, but that's not a workable solution as I move from location to location.  Is there a method that allows me to confidently use Cox email overseas on my android or am I forced to another email service?