Question : External DNS Question/Issue

Hello Experts

I am hoping that I can obtain some advice from you about a particular issue i am having.

Problem:
The site we register our domain through had old information and was unable to contact us regarding renewing our domain name. Since they could not contact us they disabled the domain and everything stopped working (website, email, etc.). I figured out the problem and paid the money to renew the domain name. The damage had already been done all the external DNS had been propagated across the internet and it took several hours for everything to start working again.
It has now been over 24 hours and there are still a couple of issues. I have 2 users saying that people are unable to email them.
Is this cause for concern?

One of the users has received an email from a specific person who was having problems so an email made it through BUT she tells me that they are still having problems sending emails to her they are not coming through. Is that normal can one email make it through and other not make it. When I look in the log it shows that the email was sent at 8AM and she received it at 11AM.

Does anyone have any advice for my situation?

Am I worrying about nothing and just need to give it more time?

Answer : External DNS Question/Issue

Other parties' mail servers will initially perform a lookup against your DNS server in order to determine where to send mail. They will cache the response received from your DNS server for performance's sake.  Your DNS server can specify the maximum length of time your domain records may be cached; once that time period has elapsed external clients will re-obtain fresh information from your DNS server.