You cannot expand fields.  Tell your customers to get shorter emails, over 50 characters is ridiculous.  If they want you to reprogram email logic using Orchid Extender, tell them it will take $10K of custom programming.

an optional field can have 60 characters

You could also make use of distribution groups. If you're using Exchange, you could create a distribution group for that customer called something like: EmailsFor1200.  And put the email addresses in the group.  Then, in Sage, send the email to the distribution group "EmailsFor1200" and Exchange will send it to the addresses within the group.

I agree with Jay that a single email address over 50 characters is crazy.  If you’re combining multiple email addresses into a single field, use the Multiple Contacts feature in current versions of Sage instead, or Tairox Extended Customers if you’re on an older version.