Gmail messages delayed to recipient

Sent emails using my gmail address are delayed up to several hours getting to one recipient! This problem started recently!

My computer: Dell, WIN-10 pro, 16GB RAM, eMClient version 9.2.2.157 (5b49542)
Internet provider: Wyoming.com


Recipient computer: Apple MAC; Internet provider: T-Mobile


what I have done to isolate the problem:
Using eMClient:
Sent message using gmail address, email arrives to recipient as much as 3 to 4 hours later!
Sent message using non gmail address. eMail arrives to recipient promptly!
Sent message to different recipient using gmail address, message arrived prompty!

Logged onto webmail at Google:
Sent message from Google server using gmail address, message arrives promptly!

I can work around this but I would appreciate any advise I can get to solve the problem!

That just sounds like a local ISP to Gmail to T-Mobile server slow mail routing issue currently, where there is delays between mail servers.

Usually those type of things resolve themselves. If it doesn’t resolve after 24-48 hours, contact your local ISP to do testing to Gmail & T-Mobile.

Apart from that also try powering off an on your local modem / router and any lan switches in your house incase you also have an old IP address which sometimes can also fix delays.

Sending from gmail server to t-Mobile server has been checked out, no delay!
Been happening for a while . Only happens to one recipient! No delay when sending to other recipients!
If I use my non gmail address in eMClient, there is NO DELAY to this one recipient that is delayed with gmail!

What is the receipient mail server ?

Just got a message from GMail saying that my messages are delayed!
“The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. Please resend your message at a later time. If the user is able to receive mail at that time, your message will be delivered. For more information, please visit Limits for sending & getting mail - Gmail Help
RECIPIENT ONLY RECEIVES 3 OR 4 EMAILS A DAY!

Just got a message from GMail saying that my messages are delayed!

The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. Please resend your message at a later tim

Sounds like that specific recipient has either got on a eg Spam list and is being bombarded with emails or has for whatever reason just started to get a serious amount of email per hour / per day more than normal so now is restricted receiving.

Suggest to send to their alternative email address if they have one till they get the problem resolved.

Thanks for your assistance!