Congratulations on setting up your form using the FormBuilder. I will be focusing on enhancing the reactivity of your form in my solution.

Here are the steps I have implemented:

1. Eliminated the binding on the [disabled] property as suggested in this Stack Overflow post. The console displays a warning when including the [disabled] property, advising to set 'disabled' to true during control setup in the component class to avoid errors.

When utilizing the disabled attribute with a reactive form directive, ensure to set disabled to true
during control setup in your component class to prevent 'changed after checked' errors.

Example:
form = new FormGroup({
first: new FormControl({value: 'Nancy', disabled: true}, Validators.required),
last: new FormControl('Drew', Validators.required)
});

2. Removed the onChange event handler and replaced it with logic within our ngOnInit function. We now monitor form value changes and dynamically enable or disable the appropriate controls based on the values.

      this.printListControl.valueChanges
      .pipe(
        distinctUntilChanged(),
        tap((controls: any[]) => {
          controls.forEach(({ mail, deliveryMethodId }, index) => {
            const control = this.printListControl.at(index);

            if (mail) {
              control.get("deliveryMethodId").enable({ emitEvent: false });
              control.get("recipients").enable({ emitEvent: false });
            } else {
              control.get("deliveryMethodId").setValue(null, { emitEvent: false });
              control.get("recipients").setValue(null, { emitEvent: false });

              control.get("deliveryMethodId").disable({ emitEvent: false });
              control.get("recipients").disable({ emitEvent: false });
            }

            control.get("recipients").setValidators(this.getRecipientsValidation(deliveryMethodId));
          });
        })
      )
      .subscribe();
  }
  getRecipientsValidation(deliveryMethodId) {
    return +deliveryMethodId === 178
      ? [Validators.pattern(this.emailPattern), Validators.required]
      : +deliveryMethodId === 179
      ? [
          Validators.minLength(10),
            (10),
          Validators.required
        ]
      : [Validators.required];
  }

Now, changes in the mail value trigger dynamic enabling/disabling of the deliveryMethodId and recipients controls. Additionally, validators are adjusted based on the selected delivery method.

3. Excluded pattern validations from the HTML markup in favor of utilizing Validators.pattern.

We can define the patterns as follows:

emailPattern = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;

3. Disregarded the validationErrorOnFocusOut event from the template, replacing it with static classes from Validator

    let printList = this.printListArray.map(x => {
      const { deliveryMethodId } = x;
      return this.fb.group({
        id: x.id,
        name: x.name,
        mail: x.mail,
        electronics: x.electronics,
        deliveryMethodId: x.deliveryMethodId,
        recipients: [
          x.recipients,
          {
            validators:
              deliveryMethodId === 178
                ? [Validators.pattern(this.emailPattern), Validators.required]
                : deliveryMethodId === 179
                ? [
                    Validators.minLength(10),
                    Validators.maxLength(10),
                    Validators.required
                  ]
                : [Validators.required],
            updateOn: "blur"
          }
        ]
      });
    });

Applying validation individually to each control prevents interference with other controls.

4. Finally, here's an updated snippet of the HTML structure:

<div class="custom-control custom-checkbox"
     *ngFor="let data of exampleForm.get('printList').controls; let j = index" formArrayName="printList">
  <div [formGroupName]="j">
    <table class="table table-print table-borderless">
      <tbody>
      <tr>
        <td scope="row" class="width90">{{data.value.name}}</td>

        <td class="width50">
          <input
            type="checkbox"
            name="mail"
            formControlName="mail"
          />
        </td>
        <td class="width50">
          <input
            type="checkbox"
            name="electronics"
            formControlName="electronics"
          />
        </td>
        <td class="width100">

          <select
            class="custom-select"
            formControlName="deliveryMethodId"
            name="deliveryMethodId"
            tabindex="1" (change)="dropdownSelection(j)"
          >
            <option value=null>Select One </option>
            <option
              *ngFor="let agencyType of DeliveryMethod"
              [value]="agencyType.id"
            >
              {{agencyType.label}}</option
            >
          </select>
        </td>
        <td class="width200">
          <ng-container *ngIf="data.value.deliveryMethodId == 178">
            <input type="text" class="form-control" placeholder="Email" name="Recepient"
                   formControlName="recipients" *ngIf="data.value.deliveryMethodId == 178"
                   [ngClass]="{ 'is-invalid': data.get('recipients').invalid && data.get('recipients').touched }"
                   autocomplete="off">

            <div class='invalid-feedback' *ngIf="data.get('recipients').invalid">
              Please enter valid email
            </div>
          </ng-container>
          <ng-container *ngIf="data.value.deliveryMethodId == 179">
            <input type="text"  prefix="+1 " class="form-control" placeholder="(###) ### - ####"
                   formControlName="recipients" name="recipients" autocomplete="off"
                   *ngIf="data.value.deliveryMethodId == 179"
                   mask=" (000) 000-0000" [showMaskTyped]="false"
                   [ngClass]="{ 'is-invalid' : data.get('recipients').invalid && data.get('recipients').touched }" >

            <div class='invalid-feedback'>
              Please enter valid fax number
            </div>
          </ng-container>
          <ng-container *ngIf="data.value.deliveryMethodId != '178' && data.value.deliveryMethodId != '179'">
            <input type="text" class="form-control" placeholder="Recepient" name="Recepient"
                   [ngClass]="{ 'is-invalid' : data.get('recipients').invalid && data.get('recipients').touched }"
                   formControlName="recipients"
            />
            <div class='invalid-feedback'>
              Field is required
            </div>
          </ng-container>


        </td>
      </tr>
      </tbody>
    </table>
  </div>
</div>

Explore the DEMO HERE