What could cause GMAIL messages to simply not arrive?

[LAS14]

My son and I are communicating with someone in Russia (not sure that's relevant, but who knows). We've finally figured out that he, using GMAIL simply does not get some of the messages, while I (using Outlook.com) get all of them. I've logged into his account and looked in SPAM and TRASH.... not there. This has happened on and off for a week or more (maybe longer). Any ideas about what could cause this? He has told me this happens with e-mails from other senders, but I haven't verified that for myself and he's not sure it's happening with other senders.

One thought that just occurred to me. Today's missing message had links in it. Could that be a significant variable?

tia
las

[lastlib]

1. tRump's Post office?

Seriously, I suspect that if the recipient is in Russia, the Putin regime is interfering with delivery, and could be stripping out links to outside sites.

[cayugafalls]

2. Google scans all email before delivery. Perhaps they are not allowing certain emails

to even pass through. Usually though, you will get a message like "you received mail from such@such and we did not load it into the system."

If you are not getting any notice then perhaps it is being filtered at a higher level by Google servers in Europe as it hops to the US.

Other than those ideas, I would have no other explanation.

[billh58]

3. See this site

https://windowsreport.com/gmail-account-not-receiving-emails/